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Handbook

November 2011

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59-UMC0071

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Issue

01

Mercury

iTC

Page 121

THEORY OF CONTROL LOOPS

Original Instructions

A PID controller can be made to operate in On-Off mode by setting the proportional
band (P) parameter to zero.

12.2.3

Proportional control

A proportional control system allows the heater power to be continuously varied. This
overcomes the oscillation problem produced by an on-off control system. The heater
voltage at any instant is proportional to the error between the measured temperature
and the setpoint. If the sample temperature drops, the heater voltage increases to
compensate.

A proportional control system reaches equilibrium below the setpoint. This is because
the heater output at the setpoint (when the error is zero) is zero. Thus a negative error is
required to produce enough heater output to balance the heat-losses to the
surroundings.

The temperature error can be reduced by making the proportional control apply to only a
part of the temperature range of the system. Below this proportional band the heater
voltage is at its maximum value. However reducing the proportional band too far
produces temperature oscillations (in the limit, a proportional band of zero degrees
produces on-off control).

Figure 12-2 Proportional band control

A PID controller can be made to operate in proportional-band mode by setting the
proportional band (P) parameter to a positive temperature value.

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Содержание Mercury iTC

Страница 1: ...yogenic environment controller Issue 01 November 2011 Original Instructions www oxford instruments com Oxford Instruments NanoScience Handbook 2011 Oxford Instruments Nanotechnology Tools Limited All rights reserved ...

Страница 2: ...Page 2 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions This page is intentionally blank ...

Страница 3: ...ng caution 17 1 3 Solid waste 17 2 OVERVIEW OF THE ITC 19 2 1 System description 20 2 1 1 Temperature sensor circuits 21 2 1 2 Heater circuits 21 2 1 3 Optional cooling circuit 21 2 1 4 Remote interfaces 21 2 1 5 Display and touch screen 21 2 1 6 Electrical power supply 22 3 USER INTERFACE 23 3 1 Front and rear panel controls 23 3 2 LCD display and GUI 23 3 2 1 Using the touch screen 23 3 2 1 1 In...

Страница 4: ...s page 54 3 2 14 Heater configuration page 55 3 2 15 Sweep Table page 56 3 2 16 Save File pages 57 3 2 17 Load File pages 58 4 FUNCTIONAL DESCRIPTION 59 4 1 Main components 59 4 1 1 User interface 60 4 1 2 Motherboard 60 4 2 iTC connections 60 4 2 1 Electrical power connection 60 4 2 2 Temperature sensor inputs 60 4 2 3 Outputs 60 4 2 4 Heater and sensor connections 61 4 2 4 1 Connecting thermocou...

Страница 5: ...level meter if required 79 5 4 Powering up the unit for the first time 80 5 4 1 Setting the date and time 80 5 4 2 Configuring the inputs 81 5 4 2 1 Configuring the sensor details 81 5 4 2 2 Using a generic calibration file 81 5 4 3 Configuring a heater 82 5 4 4 Configuring the heater control loop 83 5 4 4 1 Configuring manual heater control 83 5 4 4 2 Configuring automatic heater control 83 5 4 5...

Страница 6: ...s for RS232 and GPIB 95 7 2 1 Commands and responses 96 7 2 2 Numeric parameters 96 7 3 Control via ISOBUS 96 7 4 GPIB interface 97 7 4 1 Switching between RS232 and GPIB operation 97 7 4 2 Sending commands via the GPIB 97 7 4 3 Accepting responses via the GPIB 98 7 4 4 Status byte and use of a serial poll 98 7 4 4 1 RQS bit 98 7 4 4 2 BAV bit 98 7 4 4 3 MAV bit 98 7 4 4 4 Status byte update rate ...

Страница 7: ... 7 Environmental specifications 117 12 THEORY OF CONTROL LOOPS 119 12 1 General information on control loops 119 12 2 General information on temperature control loops 119 12 2 1 Open loop operation 120 12 2 2 On Off control 120 12 2 3 Proportional control 121 12 2 4 Proportional control with integral action 122 12 2 5 Proportional control with integral and derivative action 123 12 2 6 North Americ...

Страница 8: ...D 135 16 1 Description of the level meter board 135 16 1 1 Principles of operation 135 16 1 1 1 Operation of the board with a helium level probe 135 16 1 1 2 Operation of the board with a nitrogen level probe 136 16 1 1 3 Explanation why different methods are used for the two liquids 136 16 2 Installing the level meter board 136 16 2 1 Fitting the board 136 16 2 2 Connecting the sensor 137 16 3 Co...

Страница 9: ...read and understood before operating the Mercury iTC for the first time Customer support Oxford Instruments NanoScience has global customer support facilities that provide a coordinated response to customer s queries All queries are recorded on our support database and are dealt with as quickly as possible If we are not able to answer the query immediately we will contact you promptly Before conta...

Страница 10: ...to operate within the process parameter limits that are outlined in this manual The Mercury iTC is intended to be installed used and operated only for the purpose for which the Mercury iTC was designed and only in accordance with the instructions given in this manual and other accompanying documents Nothing stated in this manual reduces the responsibilities of users to exercise sound judgement and...

Страница 11: ...to the content or format have been made Oxford Instruments NanoScience s policy is one of continued improvement The Company reserves the right to alter without notice the specification design or conditions of supply of any of its products or services Although every effort has been made to ensure that the information in this manual is accurate and up to date errors may occur Oxford Instruments Nano...

Страница 12: ...r in this manual are hereby acknowledged Acronyms abbreviations and special terms A GLOSSARY of acronyms abbreviations and special terms is given at the end of this manual Revision history This is issue 01 of the Mercury iTC Handbook as shown in the footer at the bottom of each page The changes made to this document and a summary of previous issues are listed in the table below Always use the late...

Страница 13: ...ler complies with the following standards and certifications EN61010 1 Safety requirements for electrical equipment for measurement control and laboratory use EN61326 Electrical equipment for measurement control and laboratory use EMC requirements CE UL CSA China Restriction of Hazardous Substances Signed Jim Hutchins Managing Director Oxford Instruments NanoScience Limited ...

Страница 14: ...Page 14 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions PREFACE This page is intentionally blank ...

Страница 15: ...ectrical circuits to the equipment if its protective ground is disconnected There is an ground pillar on the rear panel identified by a symbol Connect the grounds of any external equipment to this pillar 1 1 2 High voltage hazard This equipment contains high voltages Isolate this equipment before removing and covers To isolate this equipment switch off the external AC electrical supply and disconn...

Страница 16: ...tions on use The equipment is not suitable for use in explosive flammable or hazardous environments The equipment does not provide protection against the ingress of water The equipment must be positioned so that it will not be exposed to water ingress 1 2 Cautions 1 2 1 Electrostatic caution This equipment contains electrostatic sensitive devices ESSD Use ESSD protective procedures in accordance w...

Страница 17: ...uate airflow around the unit 1 3 Solid waste The lithium battery on the motherboard will become solid waste if it has to be replaced Dispose of this item according to local and national regulations Caution EQUIPMENT VENTILATION If the Mercury unit is to be rack mounted to ensure an adequate airflow around the unit it is important that the back of the rack is open and the rack is not placed less th...

Страница 18: ...Page 18 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions HEALTH AND SAFETY This page is intentionally blank ...

Страница 19: ...based instrument and is controlled by an operating program software contained in flash memory The software version number is indicated by a two part number e g 1 01 The first digit of this number indicates the major version of the software and the second two digits indicate minor revisions The basic iTC includes a single input channel for one temperature sensor An additional 8 sensor inputs can be...

Страница 20: ...andbook November 2011 59 UMC0071 Issue 01 Mercury iTC Page 20 OVERVIEW OF THE iTC Original Instructions 2 1 System description Figure 2 1 is a block diagram of the iTC Figure 2 1 Block diagram of the iTC ...

Страница 21: ...eater Additional heaters can be driven by adding daughter boards 2 1 3 Optional cooling circuit The system can be configured using an open loop cooling system Temperature control is then performed using the heater only Improved stability can be obtained if the flow of cooling fluid is also controlled by the iTC An optional auxiliary I O board contains drive circuitry for a stepper motor This can d...

Страница 22: ...ructions 2 1 6 Electrical power supply The iTC automatically configures itself to match the supplied electrical power as long as the voltage and frequency are within the specified ranges No user intervention is required The iTC powers all sensors heaters and stepper motors that are connected to it ...

Страница 23: ...ontains several pages that the user can access as required 3 2 1 Using the touch screen 3 2 1 1 Initiating actions Each page of the GUI contains a number of buttons On certain pages other areas of the screen are also active To initiate an action tap the relevant button or active area once Certain system features are accessed by tapping the relevant button or active area twice These features are cl...

Страница 24: ...more menu items 3 Tap the desired menu item to select it The menu item is highlighted 4 Tap OK to select the item or Cancel to exit without selecting the item Figure 3 3 A drop down menu 3 2 1 3 Scrolling On some pages there is not enough space to display all the keys or information associated with the page This is indicated by buttons labelled either or Tap the button to scroll to the left Tap th...

Страница 25: ...pad contains the following keys Ten single digit keys and a decimal point key Del This button either deletes the character to the left of the cursor or any highlighted characters To delete the last character that has been entered tap Del once To delete a single character within the text a Tap anywhere within the entered text to position the cursor b Tap Del to delete the character to the left of t...

Страница 26: ... digit Ret Tap to save the number that has been entered CAPS Tap to enter capital letters The characters on the keypad change to match the selection Quit Tap to exit the keypad without saving the number that has been entered Each character entry key represents several characters a Tap a key once to enter the digit displayed on the key b Tap a key twice to enter the first character displayed on the...

Страница 27: ... using a numeric keypad Tap once to increase the displayed value 3 2 1 6 Button labels The labels on some buttons change depending on the configuration that is set The label on most buttons describes the present state of the unit For example the button shown on the left in Figure 3 8 is labelled Auto indicating that the function is in automatic mode Tap the button once to select Manual mode Figure...

Страница 28: ... 3 Home page When the equipment is powered on the Home page is displayed Figure 3 10 GUI home page The Home page contains the following features Six channel summary panels Each displays summary information for a channel that is enabled see Section 3 2 3 1 Plot button Tap once to plot information against time see Section 3 2 8 Control button Tap once to display control loop information see Section ...

Страница 29: ...ter if applicable Output power of the channel heater if applicable Identifier of the gas flow controller if applicable Percentage flow for the gas flow controller if applicable If the summary panel has not been configured the panel displays the name None and the value 0 0000 1 Tap the panel once to display the Channel Display Configuration Page see Figure 3 12 If the summary panel has been configu...

Страница 30: ...he page when the panel is unconfigured Figure 3 12 Channel Display Configuration page The page contains the following fields and controls Devices Select a sensor for this panel from a drop down menu Select None to clear the configuration for this panel Signals Devices Select a sensor parameter to display from a drop down menu Pair button Tap once to display the Device Pair Configuration page see S...

Страница 31: ...r nickname Heater Displays the heater that is paired with each temperature sensor Select a heater to assign it to this temperature sensor if applicable Select None to remove a heater from this configuration Flow Displays the gas flow controller that is paired with each temperature sensor Select a Gas Controller to assign it to this temperature sensor if applicable Select None to remove a gas contr...

Страница 32: ...n μW R Ω the resistance of the sensor in Ohms S Ω K the sensitivity of the sensor in ohms per Kelvin T K the temperature measured by the sensor in Kelvin V mV the sensor output voltage in mV Sensor Type Select a sensor type from a drop down menu Available types are Thermocouple a thermocouple PTC positive temperature coefficient sensor NTC negative temperature coefficient sensor Diode a diode sens...

Страница 33: ...ibrate button Tap once to calibrate this measurement circuit This routine takes approximately one minute An error message is generated if the calibration fails for any reason 3 2 6 2 Generic Sensor Adjustment page This page allows the user to adjust the calibration curve of a generic sensor See Section 5 4 2 2 for a detailed explanation of this process Figure 3 15 Generic Sensor Adjustment page Th...

Страница 34: ...ium tab Figure 3 16 Level Meter Sensor Details page Helium tab The page contains the following fields and controls Resistance at 0 Ω Enter the resistance of the sensor when the level is 0 Resistance at 100 Ω Enter the resistance of the sensor when the level is 100 Pre pulse Amplitude mA Enter the pre pulse amplitude in mA Pre pulse Duration s Enter the duration of the pre pulse in seconds Measure ...

Страница 35: ...elds and controls Frequency at 0 Hz Enter the frequency of the sensor when the level is 0 Frequency at 100 Hz Enter the frequency of the sensor when the level is 100 Pulse Counting Period ms Enter the time period to be used for counting the sensor pulses Increasing the period improves the accuracy but lengthens the response time Decreasing the period degrades the accuracy but shortens the response...

Страница 36: ...page 2 If a plot is displayed tap the plot area once The Plot Configuration page appears as an overlay on the Plot page Figure 3 18 Plot Configuration page The page contains the following fields and controls Device Select a device from a drop down menu Signal Select a signal to display from a drop down menu Close Tap once to close the Plot Configuration page without saving any changes that have be...

Страница 37: ...e Section 3 2 9 3 2 8 1 Adjusting the plot scaling To adjust the scaling of a plot 1 Place a finger on the region of interest of the plot The re scaled plot will be centred around this position 2 Drag the finger to zoom in and out around the area of interest a Drag the finger to the right to expand the X axis zoom in b Drag the finger to the left to contract the X axis zoom out c Drag the finger u...

Страница 38: ...oop Configuration page This page allows the user to configure a control loop A control loop uses a temperature sensor to measure the sample temperature and an associated heater or gas controller to control the sample temperature An error message is displayed if this page is accessed and neither a heater nor gas controller have been configured for this sensor Figure 3 21 Control Loop Configuration ...

Страница 39: ... set a temperature setpoint in Kelvin in this field PID Select either Manual or Automatic PID values see Chapter 12 for information on PID control loops P If PID is set to Manual enter a P parameter value in K in this field If PID is set to Automatic this field displays the P parameter value that has been obtained from the PID table I If PID is set to Manual enter an I parameter value in minutes i...

Страница 40: ...m a drop down menu TES Enter the Temperature Error Sensitivity as a power of 2 e g enter 7 to set 512 27 TES controls how fast the needle valve responds to a temperature error Increasing TES by 1 increases the response rate by a factor of 2 TVES Enter the Temperature Voltage Error Sensitivity as a power of 2 e g enter 6 to set 256 26 TVES controls how fast the needle valve responds to a heater vol...

Страница 41: ...0 to 100 valve opening enter a value of 0 i e valve steps 216 20 Similarly to set 214 steps for 0 to 100 valve opening enter a value of 2 i e valve steps 216 22 For a typical stepper motor gearbox combination used on OINS systems 216 steps would correspond to 3 complete needle valve shaft revolutions 215 steps would correspond to 3 2 1 5 complete revolutions etc However this may vary from system t...

Страница 42: ...K T2 K must be greater than T1 K P K Enter the width of the proportional band in K I mins Enter the I Integral parameter in minutes D mins Enter the D Differential parameter in minutes The page contains the following buttons Tap once to delete the currently selected row from the table A confirmation message is displayed before the row is deleted Tap OK to delete the row Tap Cancel to exit without ...

Страница 43: ...is displayed until the user navigates to another page Remote Access Select Local from the drop down menu to allow the user to control the iTC from the GUI Select an interface from the drop down menu to enable remote control via the selected interface SCPI Legacy field This field is only displayed if an interface is selected in Remote Access Select SCPI to use a command set based on SCPI Signal Ori...

Страница 44: ...ction 4 1 1 Timeout value sec Set the time that must elapse in seconds before the display brightness changes This field is only displayed if Auto Dim Option is set to Sensor Auto Dim Enter a percentage brightness value for the display when it is automatically dimmed Auto Dim must be less than or equal to Brightness Brightness Select a percentage value from the drop down menu to alter the brightnes...

Страница 45: ...able lists which boards are fitted in which slot The columns show Row number The number of the slot ID The ID of the board fitted in this slot Type The type of board fitted in this slot Name The name of the board fitted in this slot Serial Number The serial number of the board fitted in this slot The page contains the following buttons Alarm Tap once to access the Alarm Logs page see Section 3 2 1...

Страница 46: ...n menu Data Select the number of data bits for the RS232 interface from the drop down menu Parity Select a parity scheme for the RS232 interface from the drop down menu Stop Select the number of stop bits for the RS232 interface from the drop down menu Flow Control Select a flow control scheme for the RS232 interface from the drop down menu The page contains the following buttons Alarm Tap once to...

Страница 47: ...t connection Gateway If DCHP is set Off enter the gateway address that is to be used for the iTC ethernet connection DHCP Select if DHCP is to be used or not If DHCP is set to On the iTC is automatically assigned an ip address subnet mask and gateway from the network If DHCP is set to Off the values entered in the IP Address Subnet and Gateway fields are used MAC Address The MAC address of the iTC...

Страница 48: ...ddress for this instrument from the drop down menu The page contains the following buttons Alarm Tap once to access the Alarm Logs page see Section 3 2 13 3 2 12 6 GPIB Settings tab The page contains the following fields and controls GPIB Address Select a GPIB address for this instrument from the drop down menu The page contains the following buttons Alarm Tap once to access the Alarm Logs page se...

Страница 49: ...g Hour Value offset Enter a positive or negative offset value for the chosen parameter The chosen offset value is added to the Date time field The displayed date automatically changes if the offset value moves the time past 24 hours e g If the present time is shown as 15 21 17 an offset of 2 hours will change the time to 17 21 17 An offset of 9 hours advances the date by one day and the time to 00...

Страница 50: ...es into the controller from a USB memory stick The page contains the following fields Select Calibration Type Select the type of calibration file to be loaded Select Calibration File Select the file to be loaded from the memory stick Once selected the file is loaded automatically The page contains the following buttons Alarm Tap once to access the Alarm Logs page see Section 3 2 13 ...

Страница 51: ...y stick The page contains the following fields and controls Firmware Device Select the board to update from a drop down list Firmware File Select the file on the memory stick to load onto the daughter board Download F W Loads the firmware onto the selected daughter board Restart F W Restarts the daughter board firmware to allow normal operation The page contains the following buttons Alarm Tap onc...

Страница 52: ...assword is abc123 The user can change this password if required The page contains the following fields and controls Password Enter the engineering password and tap Enter Note that the password is case sensitive e g abc123 and aBc123 are different passwords Alarm Tap once to access the Alarm Logs page see Section 3 2 13 If the login is successful two additional buttons appear Change Tap to change t...

Страница 53: ...onfiguration as a restore point This allows the present configuration to be restored at some future date Each restore point is identified by an integer Drop down menu Select a saved restore point to load Loading a restore point changes the unit s configuration to the saved configuration NOTE Restore point 0 is the factory configuration The page contains the following buttons Alarm Tap once to acce...

Страница 54: ... page This page displays a table of alarms that have been generated on the system Figure 3 27 Alarm Logs page This table has the following columns Date Time The date and time when the alarm was raised Device UID The identifier of the device that raised the alarm Alarm A brief description of the alarm e g Short circuit ...

Страница 55: ...e maximum voltage to be applied to the heater Tap this field once to display a numeric keypad and enter a new value Res Ω The electrical resistance of the heater in ohms Tap this field once to display a numeric keypad and enter a new value P W This field displays the power that is currently being applied to the heater both in watts and as a percentage of the maximum This value cannot be edited The...

Страница 56: ...er to configure a temperature sweep profile Figure 3 29 Sweep Table page with an empty table Figure 3 30 Sweep Sequence Editor page with two rows of data The page displays a sweep table If the table is empty only the first row is displayed see Figure 3 29 If the table contains data one or more rows of values are displayed see Figure 3 30 ...

Страница 57: ...ore the row is deleted Tap OK to delete the row Tap Cancel to exit without deleting the row Save Tap once to save the table see Section 3 2 16 Load Tap once to load a table that has been previously saved see Section 3 2 17 Close Tap once to exit without saving changes to the table Add another row to the table The new row is appended after the last row 3 2 16 Save File pages There are several pages...

Страница 58: ...ction in the same way so only one is described in this section Figure 3 32 Load File page This page contains the following fields and controls Main area Displays a list of the existing files of this type Tap a filename to select it The name of the selected file is displayed in the Filename field Filename If desired tap once to enter the name of the file that you wish to load Load Tap once to load ...

Страница 59: ...high 19 inch rack or desktop enclosure a user interface see Section 4 1 1 a power supply a motherboard PCB which contains the basic unit functionality see Section 4 1 2 optional additional temperature sensor input s on daughter boards See Section 4 2 2 optional additional heater output s on daughter boards See Section 4 2 3 optional auxiliary I O stepper motor drive and logic I O optional GPIB IEE...

Страница 60: ...D connector on the rear panel of the iTC Sensor connections are listed in Table 4 1 The basic iTC includes a single input channel for one temperature sensor An additional 8 sensor inputs can be added to make a total of 9 inputs The unit can accept the following sensor types Negative temperature coefficient NTC resistance Positive temperature coefficient PTC resistance Thermocouple Silicon diode Ea...

Страница 61: ...les must be connected using the correct wire type to ensure measurement accuracy 4 2 5 Communications interfaces Connectors for the communications interfaces are located on the rear panel of the iTC The unit has the following interfaces Serial RS232 ISOBUS see Section 4 2 5 1 Serial2 USB see Section 4 2 5 3 GPIB IEEE 488 optional see Chapter 17 Ethernet 10 100 IEE802 3 see Section 4 2 5 4 Table 4 ...

Страница 62: ...gnals to be present on the RTS or DTR pin 20 lines The RTS signal is fed back to the computer as CTS The iTC sends logic high levels 5 V to the computer on DSR and DCD Voltage levels for the transmitted and received data are listed in Table 4 4 Table 4 3 RS232 connections on the iTC Pin Signal Name Notes 1 FG Linked to chassis ground inside the iTC 2 TD Data from the computer to the iTC 3 RD Data ...

Страница 63: ...ernet interface The ethernet interface is connected via an RJ45 connector on the rear panel The iTC can be configured to use a fixed ipaddress or to use dynamic host configuration protocol DHCP 4 3 Daughter boards The iTC can accept up to 8 daughter boards These can consist of combinations of the following board types Temperature sensor A board containing a single temperature sensor interface A ma...

Страница 64: ...acent to the power supply unit in the iTC Figure 4 2 Expansion slots in the iTC 4 3 2 Positioning daughter boards The following boards can be positioned in any location Level sensor board Auxiliary I O board Temperature sensor board that is not used to control a heater A GPIB board must be fitted in the dedicated GPIB expansion slot see Figure 4 2 A heater board must be positioned in slot 1 2 or 3...

Страница 65: ... fitted in the corresponding slots listed in Table 4 5 A control loop must be configured before a heater board can be operated Any temperature sensor can be configured to control any heater as long as the hardware is connected to match this configuration For example a If a single heater board is fitted in slot 2 a temperature sensor board must be fitted in slot 7 The control loop must be configure...

Страница 66: ...nsor and measures the voltage produced using a 4 wire measurement Resolution to 1 mK is possible at low temperatures if a suitable resistor and energisation current are used Semiconductor resistance thermometers The resistance of semiconductor resistors decreases with increasing temperature The relationship is non linear The iTC uses a 4 wire connection applying a constant voltage across the resis...

Страница 67: ...DS 32 Silicon diode OI 2 to 300K DS 31 Silicon diode LS 2 to 300K CC 35 C glass CR500 2 to 300K CA 21 100R Allen Bradley 4 to 250K CA 22 270R Allen Bradley 4 to 250K CS 01 470R Speer 0 25 to 9 999K 1 The Lin and Null ranges are general purpose ranges that may be configured for any required span and zero Both ranges provide a linear relationship between input and display The Lin range is unipolar w...

Страница 68: ...measurement The displayed sensor value is an average of the results from the last two measurements Thus every measurement is an average of values measured with positive and negative excitation currents Soft edge This is similar to bipolar excitation except the current ramps between the positive and negative values The current is maintained at a stable value between the ramps to allow a measurement...

Страница 69: ...0 and applied to the upper end of the sensor resistor The lower voltage is buffered by U15 and applied to the lower end of the reference resistor The same current thus passes through the sensor and the reference resistor U13 and either U14 or U16 measure the voltage across the reference resistor and pass these feedback signals back to U10 and U15 This ensures that the voltage across the reference ...

Страница 70: ...rement mode Constant current measurement mode is used with sensors that have a positive temperature coefficient Figure 4 4 Block diagram of constant current measurement mode The sensor and a reference resistor either R44 or R45 are connected in series Digital to analogue converters DACs U24 and U25 generate an upper and lower demand voltage This voltage is equal to the required current multiplied ...

Страница 71: ...configuration produces a ratiometric measurement technique The resistance of the sensor is Rsensor Rref x ADCnorm x RefGain ADCgain Where Rref is the reference resistance either 2kΩ or 80kΩ ADCnorm is the ADC reading normalised to the range 0 to 1 V RefGain is the interpolated gain from the calibration tables ADCgain is the gain setting of the ADC The measurement accuracy of this circuit does not ...

Страница 72: ...al to the demand voltage generated by U24 and U25 U13 and either U14 or U16 measure the voltage across the reference resistor This differential voltage is scaled by a reference gain multiplier whose gain is selected to give an output in the range 1 V to 2 5 V This voltage is then passed to the reference voltage inputs of the ADC U12 This circuit configuration produces a ratiometric measurement tec...

Страница 73: ...ifier PGA with five gain settings 1 8 16 64 and 128 An autocalibration is performed for each range The reference gain multiplier is also programmable with eight gains 1 2 4 8 16 32 64 and 128 Each gain is calibrated at low and high reference voltages 1 2 V and 2 4 V The exact gain that is used for calculating sensor resistance is a linear interpolation between these two values It is only necessary...

Страница 74: ... fed to the linear amplifier which outputs the heater drive 0 40 V 0 2 Amp The measured upper and lower heater voltages are divided by 20 and fed back to ADC U12 U12 sends the resulting voltage back to the microcontroller U24 The lower heater voltage signal passes to ground through a 0 1Ω resistor The voltage across this resistor is equal to the heater current divided by 10 This voltage is also fe...

Страница 75: ...d current is too high the current trip circuit latches on and disables the linear amplifier The linear amplifier is also disabled if regular pulses are not received from the microcontroller referred to as the dead man s handle feature 4 6 2 2 Calibrating the heater circuit The ADC performs an internal self calibration routine when the user requests a calibration This calibrates each gain range 1 8...

Страница 76: ...Page 76 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions FUNCTIONAL DESCRIPTION This page is intentionally blank ...

Страница 77: ...d in a rack ensure that the rear of the rack is open Site the rack at least 30 cm from a wall or other obstruction to ensure adequate airflow around the unit Caution CHECK THE SUPPLY VOLTAGE Check that the voltage supplied to the equipment is within the specified range Operating the equipment with an incorrect voltage may cause permanent damage CONTRÔLER LA TENSION D ALIMENTATION Contrôler que la ...

Страница 78: ...cable set must be suitable for purpose and must have a current rating at least 125 that of the equipment rating In Canada the cable set must be certified by CSA Green yellow covered conductors must only be used for connection to protective ground terminals 5 3 1 Connecting the heaters and sensors 1 Connect all sensors as described in Section 4 2 4 2 Connect all heaters as described in Section 4 2 ...

Страница 79: ... or outputs to the port on the auxiliary I O daughter board 5 3 4 Connecting the level meter if required Referring to Section 16 2 2 connect a level sensor to the relevant port on the level meter daughter board Caution CABLE DISCONNECTION Do not connect or disconnect GPIB cables while the computer or any of the instruments are powered up Equipment damage can result if this precaution is not observ...

Страница 80: ...croll the tabs until the Clock tab is displayed 5 Tap Clock The Clock Settings tab is displayed see Section 3 2 12 7 6 Check the date and time that are displayed 7 To change the date or time a Select the parameter to be changed e g Hour b Enter a positive or negative offset value and tap Apply to save the change c Repeat steps a to b until the displayed time is correct Example The currently set ti...

Страница 81: ...me page The Sensor Details page is displayed 2 Tap the Sensor Type field and select a sensor type from the drop down menu 3 Tap the Calibration field and select a calibration file from the drop down menu If you select the Generic calibration file you can adjust the calibration to suit a particular sensor see Section 5 4 2 2 4 Tap the Excitation field and select an excitation mode from the drop dow...

Страница 82: ...ustment As these adjustments are not independent re check the high resistance point after the offset has been adjusted A few iterations of these adjustments may be required to achieve the desired accuracy Procedure for using a generic calibration file You need a method of maintaining the temperature sensor at two known temperatures T1 and T2 to perform this calibration This procedure calibrates th...

Страница 83: ...Select the sensor that you want to configure in the Sensor field NOTE An error message is displayed if you haven t configured a heater for the selected sensor 3 Tap the Heat button to select either Manual or Auto Control Manual configures the heater for open loop control Auto configures the heater and associated temperature sensor in a closed control loop see Section 12 2 1 5 4 4 1 Configuring man...

Страница 84: ... the relevant cell in the Flow column and select a gas controller from the drop down menu 5 Tap Assign to save the configuration 6 Tap Home to return to the Home page 7 Tap Control The Control Loop Configuration page opens see Section 3 2 9 8 Select the sensor that you want to configure in the Sensor field NOTE An error message is displayed if you haven t configured a heater for the selected senso...

Страница 85: ... tests fails refer to Chapter 9 for troubleshooting information 1 Switch on the iTC 5 5 1 Testing the temperature sensor inputs 1 Check that the temperature displayed on each of the connected temperature sensors is correct 5 5 2 Testing the heater output 1 Tap Control on the Home page The Control Loop Configuration page is displayed 2 Select the required temperature sensor in the Sensor field 3 Se...

Страница 86: ...Page 86 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions GETTING STARTED This page is intentionally blank ...

Страница 87: ... sensor in the Sensor field 3 Tap the Heat button until it displays Auto 4 Tap the Set K button until it displays Manual 5 Enter the new setpoint in the Set K field 6 Tap Home to return to the Home page 6 2 2 Changing a gas flow setpoint 1 Tap Control on the Home page The Control Loop Configuration page is displayed 2 Select the required temperature sensor in the Sensor field 3 Tap the Flow button...

Страница 88: ... in K for the first step in the Final T K field in row 1 of the Sweep Sequence Editor 6 Enter the time for the first ramp in minutes in the Time To Final T mins field in row 1 of the Sweep Sequence Editor 7 Enter the time to hold the step temperature in minutes in the Hold At Final T mins field in row 1 of the Sweep Sequence Editor 8 Tap to add an additional row to the table 9 When the complete se...

Страница 89: ...value is held at its present value 6 4 Using the plot function 6 4 1 Configuring a plot 1 Tap Plot on the Home page The Plot Configuration page is displayed 2 Tap Device and select the first device to be used 3 Tap Signal and select the first signal to be plotted 4 Tap Save to plot the first signal 5 To add traces to the plot double tap anywhere on the plot area and repeat steps 2 to 4 6 If requir...

Страница 90: ... 4 3 To exit the plot 1 Double tap anywhere on the page The Plot Configuration page is displayed 2 Tap Home to return to the Home page 6 5 Configuring external interfaces Only one external interface can be used at a time refer to the relevant section for information on configuring an external interface 6 5 1 Configuring the ethernet interface if required 1 Obtain the required ethernet settings fro...

Страница 91: ... is to be used scroll to the ISOBus tab 9 Set the ISOBUS address to a value between 1 and 8 10 Tap Apply 11 To enable the interface see Section 6 5 5 6 5 3 Configuring the GPIB if required 1 Tap Settings on the Home page 2 Scroll to the GPIB tab 3 Enter a GPIB address value between 0 and 31 NOTE Every unit connected to the GPIB must have a different GPIB address 4 Tap Apply 5 To enable the interfa...

Страница 92: ...es field and select None from the drop down menu 3 Tap Assign 4 The panel on the Home page should now display the name None 6 6 2 Re configuring a sensor 1 Tap a configured panel on the Home page 2 Edit the sensor details on the Sensor Details Screen page 3 Tap Home to return to the Home page 6 6 3 Re configuring a heater 4 Tap Heater on the Home page 5 Edit the displayed values for the heater tha...

Страница 93: ... until it displays Manual 3 Tap the P field and enter a new proportional band value in K if required Enter 0 for On Off control 4 Tap the I field and enter a new integral value in minutes if required Enter 0 to turn off the integral action 5 Tap the D field and enter a new derivative value in minutes if required Enter 0 to turn off the derivative action 6 Tap Home to return to the Home page 6 7 2 ...

Страница 94: ...Page 94 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions BASIC OPERATING INSTRUCTIONS This page is intentionally blank ...

Страница 95: ...the GPIB interfaces All commands consists of a string of printing ASCII characters terminated by a Carriage Return character A Line Feed may optionally be sent after the Carriage Return but the iTC ignores it Unless a command starts with a dollar character all commands evoke a response from the iTC The response consists of a string of one or more printing ASCII characters terminated by a Carriage ...

Страница 96: ... the present status of the iTC to prevent this type of error 7 2 2 Numeric parameters All numeric parameters are treated as signed decimal numbers and are sent as a string of decimal digits with a decimal point in the appropriate place 7 3 Control via ISOBUS To allow separate instruments on the bus to be distinguished each instrument is allocated a unique address in the range 0 to 9 When more than...

Страница 97: ...on zero password is sent first This is to avoid accidentally changing an instrument address 7 4 GPIB interface The GPIB interface supplements rather than replaces the RS232 serial interface An instrument can be controlled either by GPIB or by RS232 but not by both simultaneously 7 4 1 Switching between RS232 and GPIB operation If the iTC is using RS232 and GPIB has not been deliberately disabled t...

Страница 98: ...occurs A better method is for the GPIB controller to read a status byte from the iTC by conducting a serial poll The iTC always returns a status byte when a serial poll is conducted Three bits in the status byte are significant Bit 6 value 64 decimal RQS requesting service Bit 4 value 16 decimal MAV message available Bit 1 value 2 decimal BAV byte available 7 4 4 1 RQS bit The position of the RQS ...

Страница 99: ...ties all communication buffers It does not reset any of the temperature control functions Device Clear can thus be safely used to empty the communication buffers of any unread messages Device Clear can be sent by either the GPIB DCL message which clears all connected devices or by the GPIB SDC message which only clears the addressed device 7 4 7 Use of the interface clear function When the iTC rec...

Страница 100: ...y 7 4 10 1 Timeouts All commands that attempt to write or read data to an instrument must have a Timeout facility built in This ensures that the bus only waits a specified time period for a response from an instrument When a timeout occurs the controller must conduct a serial poll to attempt to discover what has caused the timeout If the serial poll also generates a timeout the controller must res...

Страница 101: ...ove dust or any marks Do not use solvents or abrasive cleaning products 8 1 2 Calibrating the temperature sensor circuits This procedure calibrates the electronics in each temperature sensor circuit that is fitted to the iTC It does not calibrate the external temperature sensors 1 Locate the summary panel on the Home page for the first temperature sensor circuit to be calibrated 2 Tap the panel on...

Страница 102: ...Page 102 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions PREVENTIVE MAINTENANCE This page is intentionally blank ...

Страница 103: ...s programmed Check the relevant Sensor Details page Bad temperature sensor connection Check the sensor connections Incorrect excitation current programmed Check the programmed excitation current on the relevant Sensor Details page Incorrect calibration file is selected Check the correct calibration file is selected on the relevant Sensor Details page The displayed temperature does not change when ...

Страница 104: ...Page 104 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions TROUBLESHOOTING This page is intentionally blank ...

Страница 105: ...se commands were used in previous temperature controller models e g ITC503 The user configures the iTC to use one set or the other It is recommended that new applications use the SCPI command set as these commands provide greater functionality The legacy command set is provided so that the iTC is compatible with any existing remote applications that have been written to drive older OINS equipment ...

Страница 106: ...lies to both these verbs with a STAT status verb If responding to a READ verb the STAT verb is followed by the requested data If responding to a SET verb the STAT verb is followed by the value set 10 3 4 Nouns Elements within the iTC are addressed by a hierarchical structure A Board contains a number of Devices A Device contains a number of Signals The structure of NOUNS reflects this Where UID is...

Страница 107: ...our clock Read Set hh mm ss DATE date Read Set yyyy mm dd MAN manufacturing designator N A HVER hardware version Read only version number FVER firmware version GUI APP Read only version number SERL unit serial number Read only alphanumeric MODE mode of operation NORM ENG Read Set enumerated value PASS engineering mode password Set alphanumeric Required to enter ENG mode FLSH amount of free space i...

Страница 108: ...icates the motherboard has one temperature sensor in id0 and one heater in id1 A system with one set of daughter boards might return the following STAT DEV MB0 TEMP DEV DB1 TEMP DEV MB1 HTR DEV DB2 HTR DEV DB3 AUX DEV DB4 LVL This message indicates that there are two temperature sensors two heaters one auxiliary I O board and one level sensor 10 3 4 2 Addressing a temperature sensor To address a t...

Страница 109: ...PE INVALID MAG INVALID CALB RP5 DAT NOTE All the new settings that are valid are set All the new settings that are invalid are not changed TYPE Excitation type UNIP BIP SOFT Read set Enumerated set MAG Excitation magnitude Read set Float value followed by a scale CAL Calibration designator N A FILE Calibration file name Read set Filename INT Interpolation type LIN SPL LAGR Read set Enumerated set ...

Страница 110: ...g a level meter sensor To address a level meter sensor use the following structure DEV UID LVL Where UID is a unique identifier that is allocated to each board based on its SPI location HTR Heater controller designator N A MAN Manufacturing designator N A HVER Hardware version Read only version number FVER Firmware version Read only version number SERL Serial number Read only alphanumeric NICK Nic...

Страница 111: ...e pulse amplitude mA Read set float value TIM Pre pulse duration s Read set float value PULS Measurement pulse N A MAG Measurement pulse amplitude mA Read set float value TIM Measurement pulse duration s Read set float value DEL Measurement pulse delay s Read set float value NIT Nitrogen probe N A FREQ Frequency configuration N A ZERO Frequency at 0 Hz Read set float value FUL Frequency at 100 Hz ...

Страница 112: ...designator N A HVER Hardware version Read only version number FVER Firmware version Read only version number SERL Serial number Read only alphanumeric GMIN Minimum gas flow setting Read set float value 0 0 to 20 0 GFSF Gas flow scaling factor Read set float value 0 0 to 99 0 TES Temperature error sensitivity Read set float value 0 0 to 20 0 TVES Temperature voltage error sensitivity Read set float...

Страница 113: ...sociated with the loop Read set UID put 0 to unset AUX ID Auxiliary board associated with the loop Read set UID put 0 to unset LVL ID Level meter associated with the loop Read set UID put 0 to unset ENAB Loop enabled heater auto on off Read set OFF ON HSET Percentage heater output Read set 0 0 to 100 0 TSET Temperature setpoint Read set Cold limit to hot limit PIDT PID auto use PID table zone cont...

Страница 114: ...Page 114 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions COMMAND REFERENCE GUIDE This page is intentionally blank ...

Страница 115: ...Mains supply voltage 100 VAC to 240 VAC Mains supply frequency 50 Hz to 60 Hz Maximum supply power 650 W Maximum mains voltage fluctuation 10 of nominal voltage Category II transient overvoltages can typically be present on the mains supply Table 11 3 Specifications of sensor inputs Item Specification Basic unit single sensor input Upgradeable to 17 sensor inputs NTC resistance range 5 Ohms to 200...

Страница 116: ...e output is filtered with co wound inductors and decoupling capacitors The output is protected against short circuits The unit has a dead man s handle timer that disables the heater outputs if the control loop stalls 11 5 PC interfaces Table 11 4 Specifications of heater outputs Item Specification Basic unit heater outputs Single fully controlled 80 W output Upgradeable to 4 fully controlled 80 W ...

Страница 117: ...l isolation specifications Item Specification Sensor terminals to chassis 50 VDC Heater terminals to chassis 50 VDC Communications 0 V to chassis 50 VDC Communications to sensor or heater 50 VDC Table 11 7 Environmental specifications Item Specification Recommended ambient temperature 20 C to 30 C Ambient temperature with reduced performance 0 to 40 C Shipping and storage temperature 30 C to 85 C ...

Страница 118: ...Page 118 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions TECHNICAL SPECIFICATIONS This page is intentionally blank ...

Страница 119: ... slow response to rapid rises in temperature Automatic control of both the gas valve and the heater output This usually provides the most stable control as it can compensate quickly for rapid rises or falls of temperature 12 2 General information on temperature control loops A temperature control system consists of the following parts A means of measuring the sample temperature the temperature sen...

Страница 120: ...ol is obtained by setting the Heat field on the Control Loop Configuration page to Manual mode see Section 3 2 9 An example of open loop control is a hot plate on a domestic oven 12 2 2 On Off control In an on off control system the heater power is either maximum if the measured temperature is below the setpoint or zero if the measured temperature is above the setpoint The control accuracy and con...

Страница 121: ...portional control system reaches equilibrium below the setpoint This is because the heater output at the setpoint when the error is zero is zero Thus a negative error is required to produce enough heater output to balance the heat losses to the surroundings The temperature error can be reduced by making the proportional control apply to only a part of the temperature range of the system Below this...

Страница 122: ...d to act more slowly than the response of the heater to avoid oscillations The control response of this system may be slow because of this The response of the integrator is characterised by the integrator action time This is referred to as the I parameter in the PID control loop Figure 12 3 Proportional control with integrator action If the setpoint increases by a large amount the integrator outpu...

Страница 123: ...um control output to zero Figure 12 4 Proportional control with integral and differential action Some control systems may have sufficient control response without using derivative action A PID controller can be made to operate in this mode by setting the proportional band P parameter to a positive temperature value the integral I parameter to a non zero action time and the derivative D parameter t...

Страница 124: ... 7 1 PID table operation Figure 12 5 shows an example PID table containing two rows The values shown in this table are not from a real system Figure 12 5 PID table operation 12 2 7 2 Entering a PID table 1 Tap the panel on the Home screen that is to be configured The Control Loop Configuration page is displayed 2 Tap the PID field and set it to Auto 3 Tap PID Table The PID Table Editor page is dis...

Страница 125: ...alve which controls the flow of a cooling gas Controlling the gas flow regulates the cooling power which provides control of the sample temperature 12 3 2 Manual control of the gas flow When the gas control is set to MANUAL mode the valve is driven to a fixed position to provide constant cooling power Temperature control is then provided by controlling the heater output 12 3 3 Automatic control of...

Страница 126: ...control of temperature near the setpoint is dominated by the heater When the system is in control at the setpoint the temperature error is by definition zero Control of the valve position is thus dominated by the heater voltage error and the cooling is adjusted until the heater voltage reaches its target value The system is at equilibrium when both the temperature error and the heater voltage erro...

Страница 127: ...sor that is used to compensate for fluctuations in ambient temperature 13 2 Installing a temperature sensor board 13 2 1 Fitting the board If a temperature board is not used to control a heater it can be fitted in any expansion slot It is preferable to locate temperature boards in slots that are physically separated from any heater boards that are fitted If a temperature sensor board is to be used...

Страница 128: ... temperature board in the allocated expansion slot 8 Secure the board using the screw that was removed in step 6 9 Refit the board clamp using the two screws that were removed earlier 10 If a heater board is to be installed at the same time fit the heater board in the allocated slot 11 Fit the lid back onto the unit using the screws that were removed earlier 13 2 2 Connecting the sensor A single s...

Страница 129: ...ed in the correct slot so that it is connected to its associated temperature sensor board see Table 4 5 1 Turn off electrical power to the iTC 2 Remove the electrical power connector from the back of the unit 3 Remove the screws that secure the lid of the iTC There are 6 screws on either side panel of the iTC and 3 screws on the rear panel 4 Lift off the lid 5 Remove the two screws that secure the...

Страница 130: ... the two screws that were removed earlier 10 Fit the lid back onto the unit using the screws that were removed earlier 14 2 2 Connecting the heater The heater is connected to the 9 way D connector on the associated temperature sensor board Pin connections are listed in Section 4 2 4 On a dual sensor board the heater is only connected to the lower connector 14 2 3 Configuring the heater board See S...

Страница 131: ... 15 which is connected to the unregulated 11 V line via a diode and a fuse Pin 15 can source a maximum current of 500 mA The input lines on the auxiliary port can either be driven by TTL levels or by contact closures switching to 5 VDC A 100 kOhm pull down resistor to 0 V is fitted to each input The AutoGFS sense input must be linked to 5 VDC when an AutoGFS unit is connected If a temperature swit...

Страница 132: ... panel of the iTC and 3 screws on the rear panel 4 Lift off the lid 5 Remove the two screws that secure the board clamp Remove the board clamp Figure 15 1 Board clamp 6 Remove the screw that secures the blanking panel in the location where the board is to be fitted Keep the screw Figure 15 2 Daughter board blanking panel 7 Using appropriate ESD precautions fit the auxiliary I O board in the alloca...

Страница 133: ...d in Table 15 1 Table 15 1 Auxiliary port pin assignations Pin Function 1 Output Bit 0 Stepper Motor or Compressor Disable 9 Output Bit 1 Stepper Motor 2 Output Bit 2 Stepper Motor 10 Output Bit 3 Stepper Motor 3 Not used 11 Not used 4 Not used 12 Not used 5 Input K4 Auto GFS Sense 13 Input K5 Spare 6 Input K6 Spare 14 Input K7 Over temperature switch input 7 5 VDC 15 Driver protection 11 VDC unre...

Страница 134: ...Page 134 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions AUXILIARY I O DAUGHTER BOARD This page is intentionally blank ...

Страница 135: ... resistive while the section in the liquid is below the critical temperature and thus superconducting The length of the resistive section of the wire thus depends on the level of liquid in the reservoir To minimise heating of the sample the current in the wire is turned off after a measurement has been made Because there is zero current through the probe the whole length of wire becomes supercondu...

Страница 136: ...erent methods are used for the two liquids Liquid helium has a relative permittivity of 1 055 which is similar to the relative permittivity of helium gas at 4 2 K The capacitance probe is thus not sensitive to the liquid level when used with liquid helium It is possible to make a liquid nitrogen probe using a wire made of a high temperature superconductor However this probe would be much less robu...

Страница 137: ...p 6 9 Refit the board clamp using the two screws that were removed earlier 10 Fit the lid back onto the unit using the screws that were removed earlier 16 2 2 Connecting the sensor Connect the sensor to the appropriate 9 way D connector on the rear panel of the board The pin connections are listed in Table 16 1 Table 16 1 Level meter sensor pin connections Pin Signal Name Helium Probe Nitrogen Pro...

Страница 138: ... sensor at room temperature record the sensor resistance value that is displayed on the Home page 7 Fully immerse the sensor part of the probe in liquid helium 8 Record the sensor resistance value that is displayed on the Home page This value should be close to zero 9 Tap the configured level meter panel on the Home page The Level Meter Sensor Details page is displayed 10 Select the Helium tab Fig...

Страница 139: ...ogen sensor 1 Tap an unconfigured panel on the Home page The Channel Display Configuration page is displayed 2 Tap on the Devices field and select a level meter input 3 Tap on the Signals field and select Pulse 4 Tap Assign to save the changes 5 Tap Home 6 With the nitrogen sensor at room temperature record the sensor frequency that is displayed on the Home page 7 Fully immerse the sensor part of ...

Страница 140: ...ure with reduced performance 0 C to 50 C Altitude Up to 2000 m Vibration Fixed laboratory installation Table 16 3 Specification of the helium probe Parameter Specification Excitation current settings 20 mA to 280 mA in 20 mA steps Excitation current accuracy 5 Excitation voltage 40 V maximum Probe resistance 0Ω to 300Ω Probe resistance measurement accuracy 0 2 Probe resistance measurement stabilit...

Страница 141: ...e instrument is specified by the Capability Identification Codes SH1 AH1 T6 L4 SR1 RL0 PP0 DC1 DT0 C0 E1 17 2 Installing a GPIB board 17 2 1 Fitting the board An GPIB board can only be fitted in the dedicated GPIB expansion slot 1 Turn off electrical power to the iTC 2 Remove the electrical power connector from the back of the unit 3 Remove the screws that secure the lid of the iTC There are 6 scr...

Страница 142: ...d blanking panel 7 Using appropriate ESD precautions fit the GPIB board in the GPIB expansion slot 8 Secure the board using the screw that was removed in step 6 9 Refit the board clamp using the two screws that were removed earlier 10 Fit the lid back onto the unit using the screws that were removed earlier 17 2 2 Connecting to a GPIB board The GPIB board has a single GPIB connector Connect the bo...

Страница 143: ...0071 Issue 01 Mercury iTC Page 143 GLOSSARY Original Instructions GLOSSARY This glossary explains the acronyms abbreviations and special terms used in this Instructions for Use Manual The entries are presented in alphanumeric order ...

Страница 144: ...Programmable Read Only Memory ESSD Electrostatic Sensitive Devices EOS End of String GPIB General Purpose Interface Bus IEEE 488 GUI Graphical User Interface I O Input output LCCD Liquid Crystal Display LED Light Emitting Diode N A Not Applicable NTC Negative Temperature Coefficient PC Personal Computer PCB Printed Circuit Board PGA Programmable Gain Amplifier PTC Positive Temperature Coefficient ...

Страница 145: ...Page 145 Handbook Mercury iTC November 2011 59 UMC0071 Issue 01 Original Instructions This page is intentionally blank ...

Страница 146: ...00 Baker Avenue Suite 150 Concord MA 01742 Phone 1 978 369 9933 sales Toll Free 1 800 447 4717 Fax 1 978 369 8287 sales and support Email info ma oxinst com sales Email csg ma oxinst com support Central Europe Oxford Instruments GmbH Otto von Guericke Ring 10 D 65205 Wiesbaden Tel 49 6122 937 171 sales Tel 44 0 1865 393311 support Fax 49 6122 937 175 sales Fax 44 0 1865 393333 support Email OINS D...

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