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Lake Shore Model 625 Superconducting MPS User’s Manual

5-40

Computer Interface Operation

PSH

Persistent Switch Heater Command

Input:

PSH <mode> [term]

Format:

n [term]
<mode>

Specifies if the persistent switch heater is to be turned on or off: 0 = Heater off,
1 = Heater on, 99 = Heater on overriding output current setting check.

Remarks:

This command turns the current to the persistent switch on or off. The switch needs to be enabled and
setup using the

PSHS

command. If the output current is not the same as the current setting when the

PSH was turned off last, the PSH will not be turned on unless the

PSH 99

command was issued.

PSH?

Persistent Switch Heater Query

Input:

PSH? [term]

Returned:

<mode> [term]

Format:

n
<mode>

Specifies the current mode of the persistent switch heater: 0 = Heater off, 1 = Heater on,
2 = Heater warming, 3 = Heater cooling.

PSHIS?

Last Current Setting When PSH Was Turned Off Query

Input:

PSHIS? [term]

Returned:

<current> [term]

Format:

±

nn.nnnn

<current>

Specifies the output current of the power supply when the persistent switch heater was
turned off last. The PSH will not be allowed to turn on unless this current is equal to the
present output current or the heater is turned on using the

PSH 99

command. If 99.9999

is returned, then the output current when the PSH was turned off last is unknown.

PSHS

Persistent Switch Heater Parameter Command

Input:

PSHS <enable>, <current>, <delay> [term]

Format:

n, +nnn, +nnn [term]
<enable>

Specifies if there is a persistent switch in the system: 0 = Disabled (no PSH), 1 =
Enabled.

<current>

Specifies the current needed to turn on the persistent switch heater: 10 – 125 mA.

<delay>

Specifies the time needed to turn the persistent switch heater on or off: 5 – 100 s.

Remarks:

If there is no persistent switch heater in the system, then the switch should be disabled. This command
does not turn on the current to the persistent switch. That command is

PSH

.

PSHS?

Persistent Switch Heater Parameter Query

Input:

PSHS? [term]

Returned:

<enable>, <current>, <delay> [term]

Format:

n, +nnn, +nnn

(Refer to command for description)

QNCH

Quench Parameter Command

Input:

QNCH <enable>, <rate> [term]

Format:

n, +n.nnnn [term]
<enable>

Specifies if quench detection is to be used: 0 = Disabled, 1 = Enabled.

<rate>

Specifies the current step limit for quench detection: 0.0100 – 10.000 A/s.

Remarks:

When quench detection is enabled, a quench will be detected when the output current attempts to
change at a rate greater than the current step limit.

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Summary of Contents for 625

Page 1: ...port or relationship whatsoever has existed which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics Inc in these developments Methods and apparatus disclosed herein may be subject to U S Patents existing or applied for Lake Shore Cryotronics Inc reserves the right to add improve modify or withdraw functions design modifications or products at any time without notice Lake...

Page 2: ...Lake Shore Model 625 Superconducting MPS User s Manual A ...

Page 3: ...warranty is the only warranty applicable to the Product and replaces all other warranties or conditions express or implied including but not limited to the implied warranties or conditions of merchantability and fitness for a particular purpose Specifically except as provided herein 8 Lake Shore undertakes no responsibility that the products will be fit for any particular purpose for which you may...

Page 4: ... our product implies that you understand the Lake Shore license agreement and statement of limited warranty FIRMWARE LICENSE AGREEMENT The firmware in this instrument is protected by United States copyright law and international treaty provisions To maintain the warranty the code contained in the firmware must not be modified Any changes made to the code is at the user s risk Lake Shore will assum...

Page 5: ...Lake Shore Model 625 Superconducting MPS User s Manual D ...

Page 6: ...Lake Shore Model 625 Superconducting MPS User s Manual C ...

Page 7: ...and interface cables attached If the installation and operating instructions in the User s Manual are followed there should be no degradation in EMC performance This instrument is not intended for use in close proximity to RF Transmitters such as two way radios and cell phones Exposure to RF interference greater than that found in a typical laboratory environment may disturb the sensitive measurem...

Page 8: ...Lake Shore Model 625 Superconducting MPS User s Manual E ...

Page 9: ... 1 3 2 REAR PANEL DEFINITION 3 2 3 3 LINE INPUT ASSEMBLY 3 3 3 3 1 Line Voltage 3 3 3 3 2 Line Fuse and Fuse Holder 3 3 3 3 3 Power Cord 3 3 3 3 4 Power Switch 3 4 3 4 MAGNET CABLE CONNECTIONS 3 4 3 5 ANALOG INPUT OUTPUT CONNECTIONS 3 4 3 5 1 External Current Programming 3 4 3 5 2 Remote Voltage Sense 3 5 3 5 3 Output Current and Voltage Monitors 3 5 3 6 DIGITAL INPUT OUTPUT CONNECTIONS 3 5 3 6 1 ...

Page 10: ...ersistent Switch Heater Output Enable 4 11 4 14 2 Persistent Switch Heater Current Setting 4 11 4 14 3 Persistent Switch Heater Delay 4 12 4 14 4 Persistent Mode Ramp Rate 4 12 4 15 PSH ON OFF 4 13 4 16 QUENCH DETECTION 4 14 4 16 1 Quench Detection Enable 4 14 4 16 2 Current Step Limit 4 14 4 17 ERROR STATUS DISPLAY 4 15 4 18 EXTERNAL CURRENT PROGRAMMING 4 15 4 19 LOCKING THE KEYPAD 4 16 4 20 INTE...

Page 11: ...UMMARY 5 32 5 3 1 Interface Commands Alphabetical Listing 5 34 6 OPTIONS AND ACCESSORIES 6 1 6 0 GENERAL 6 1 6 1 MODELS 6 1 6 2 ACCESSORIES 6 1 7 SERVICE 7 1 7 1 CONTACTING LAKE SHORE CRYOTRONICS 7 1 7 2 RETURNING PRODUCTS TO LAKE SHORE 7 1 7 3 FUSE DRAWER 7 2 7 4 LINE VOLTAGE SELECTION 7 2 7 5 FUSE REPLACEMENT 7 3 7 6 ERROR MESSAGES 7 3 7 7 OUTPUT SOURCE IMPEDANCE 7 5 7 8 ELECTROSTATIC DISCHARGE ...

Page 12: ... National Instruments GPIB Configuration from IBCONF EXE 5 21 7 1 Fuse Drawer 7 2 7 2 Power Fuse Access 7 3 7 3 Location Of Important Internal Components 7 8 7 4 ANALOG I O Connector Details 7 9 7 5 PSH OUTPUT Connector Details 7 9 7 6 DIGITAL I O Connector Details 7 10 7 7 RS232 DTE Connector Details 7 10 7 8 IEEE 488 Rear Panel Connector Details 7 12 C 1 Typical Cryogenic Storage Dewar C 1 LIST ...

Page 13: ...ovides high setting resolution of 0 1 mA and flexible output programming Lake Shore chose linear input and output power stages for the moderate 300 W output of the Model 625 Linear operation eliminates the radiated radio frequency RF noise associated with switching power supplies allowing the Model 625 to reduce the overall noise in its output and the noise radiated into surrounding electronics Sa...

Page 14: ...an 2 0 V and less than 2 0 V Output Readings The Model 625 provides high resolution output readings The output current reading reflects the actual current in the magnet and has a resolution of 0 1 mA The output voltage reading reports the voltage at the output terminals with a resolution of 100 µV A remote voltage reading is also available to more accurately represent the magnet voltage by bypassi...

Page 15: ...es a trigger function that is used to start an output current ramp When the trigger is activated either by an external trigger or by computer interface command the power supply will begin ramping to the new setpoint The Model 625 provides two analog outputs to monitor the output current and voltage Each output is a buffered differential analog voltage representation of the signal being monitored T...

Page 16: ... be paralleled for 120 A 5 V operation Protection Quench Line Loss Low Line Voltage High Line Voltage Output Over Voltage Output Over Current Over Temperature Remote Inhibit on critical error conditions magnet discharges at 1 V nominal Output Programming Internal Current Setting Resolution 0 1 mA 20 bit Settling Time 600 ms for 1 step to within 0 1 mA into a resistive load Accuracy 10 mA 0 05 of s...

Page 17: ...n Open or shorted heater detection error message if off and on output currents differ Connector BNC Front Panel Display Type 8 line by 40 character graphic vacuum fluorescent display module Display Readings Output current calculated field T or G output voltage remote voltage sense Display Settings Output current calculated field compliance voltage ramp rate Display Annunciators Status and errors L...

Page 18: ...nterconnect cable kit Select a power configuration VAC 100 B Instrument configured for 100 VAC with U S power cord VAC 120 B Instrument configured for 120 VAC with U S power cord VAC 120 BC Instrument configured for 120 VAC with U S power cord and universal European power cord and fuses for 220 240 setting extra charge for this option VAC 220 C Instrument configured for 220 VAC with European power...

Page 19: ...green firmly connected to an electrical ground safety ground at the power outlet The power jack and mating plug of the power cable meet Underwriters Laboratories UL and International Electrotechnical Commission IEC safety standards Ventilation The instrument has ventilation holes in its side covers Do not block these holes when the instrument is operating Do Not Operate In An Explosive Atmosphere ...

Page 20: ...Lake Shore Model 625 Superconducting MPS User s Manual 1 8 Introduction This Page Intentionally Left Blank ...

Page 21: ...tanium is on the order of 1010 A m2 about three orders of magnitude greater than normal house wiring If the critical current density is exceeded the wire will return to its normal resistive state The last property is critical field A superconductor will return to its normal resistive state if it is exposed to a magnetic field larger than its critical field Superconducting wire such as niobium tita...

Page 22: ... is the permeability of air n is the number of turns A is the cross sectional area of the coil and l is the length of the solenoid The inductance of superconducting magnets is fairly large typically between 10 and 100 Henries The magnet s inductance limits the rate at which the magnet can be charged or discharged because of the increased voltage required to change current The formula V L di dt rel...

Page 23: ...ill continue to source current to the diodes eventually damaging them and causing them to short This would require that the protection diodes be replaced which could be a significant expense especially if the magnet is in a sealed dewar To ensure that the diodes are not damaged by the power supply the compliance voltage limit of the supply should be set to a voltage below the protection diode rang...

Page 24: ...re installed in dewars filled with liquid helium A dewar usually consists of one or more reservoirs surrounded by a vacuum jacket This vacuum jacket insulates the reservoir from room temperatures In dewars with multiple reservoirs the outside reservoir is normally filled with liquid nitrogen as a way to further reduce the heat transfer from the liquid helium filled inner reservoir Most dewars are ...

Page 25: ...ion Allowing the magnet to become uncovered can cause a quench Also the level of the helium should never be higher than the inlets of the vapor cooled current leads If the inlets are submerged in liquid helium the helium gas can no longer cool the leads and extra heat will be transferred into the helium reservoir increasing the rate of helium boil off 2 6 MAGNET QUENCH A magnet quench occurs when ...

Page 26: ...Lake Shore Model 625 Superconducting MPS User s Manual 2 6 Magnet System Design Figure 2 2 Cutaway Of A Typical Helium Dewar Magnet and Insert ...

Page 27: ...lves may be shipped as several parts The items included with the Model 625 are listed below Contact Lake Shore immediately if there is a shortage of parts or accessories Lake Shore is not responsible for any missing items if not notified within 60 days of shipment Inspect all items for both visible and hidden damage that occurred during shipment If damage is found contact Lake Shore immediately fo...

Page 28: ... pin D subminiature receptacle provides analog monitor outputs as well as analog inputs Refer to Paragraph 3 5 and see Figure 7 4 Line Input Assembly Includes the IEC 320 C14 line cord receptacle and line voltage selector with line voltage indicator and line fuse holder Refer to Paragraph 3 3 DIGITAL I O 25 pin D subminiature receptacle provides connections for digital inputs and outputs Refer to ...

Page 29: ...a fuse ever fails it is important to replace it with the value and type indicated on the rear panel for the line voltage setting The letter T on the fuse rating indicates that the instrument requires a time delay or slow blow fuse Fuse values should be verified any time line voltage configuration is changed Instructions for changing and verifying a line fuse are given in Paragraph 7 5 3 3 3 Power ...

Page 30: ... 85 2 33 6 180 0 1563 107 53 4 21 2 135 0 2485 67 34 6 13 3 100 0 3951 42 8 8 4 75 0 6282 27 3 5 ANALOG INPUT OUTPUT CONNECTIONS The Analog I O connector provides connections to analog signals used to monitor or control the power supply Two inputs are provided one to program the current output and one used to monitor the remote voltage sense leads Two outputs are also provided to monitor the outpu...

Page 31: ...INPUT OUTPUT CONNECTIONS The Digital I O connector provides connections to digital control signals Two of these connections Remote Inhibit and Trigger In are inputs used to control the state of the power supply The Fault Out is an output that is used to signal error conditions Digital_IO bmp Pin Name Pin Name 1 2 3 4 5 6 7 8 9 10 11 12 13 Fault Out Common NC Remote Inhibit Common NC Trigger Out Co...

Page 32: ... will activate it The signal is internally pulled up to allow operation with a simple switch closure Refer to Figure 3 5 3 7 PERSISTENT SWITCH HEATER OUTPUT The persistent switch heater output is a controlled DC current source capable of sourcing up to 125 mA with a jumper selectable compliance voltage limit of 15 V or 24 V The default setting is 24V Refer to Paragraph 7 11 to configure the compli...

Page 33: ...m the isolated output stage but are electronically balanced and have a common mode voltage limit of 10 V This limit is more than adequate for any equipment that is referenced to power line ground Similarly the External Current Programming and Remote Voltage inputs are differential and allow easy interface to power line grounded equipment 3 9 CONNECTING MULTIPLE UNITS IN PARALLEL Up to two Model 62...

Page 34: ...Lake Shore Model 625 Superconducting MPS User s Manual 3 8 Installation Dual_625_Rear bmp Figure 3 7 Connecting Two Power Supplies in Parallel ...

Page 35: ... the power supply it is recommended that the supply be mounted at the bottom of the rack For ventilation the back of the rack should be open and a 1U 44 mm high ventilation cover should be mounted on the rack above and below the power supply Use 19 inch rack support rails not included fastened to the front and back of the cabinet to support the weight of the supply CAUTION The front panel rack mou...

Page 36: ...Lake Shore Model 625 Superconducting MPS User s Manual 3 10 Installation This Page Intentionally Left Blank ...

Page 37: ...d in Table 4 1 When initialization is complete the instrument will begin its normal reading cycle and current or field readings should appear on the display Any error messages will appear in the bottom of the display Messages listed in Table 7 1 Instrument Hardware Errors are related to the instrument hardware and may require help from Lake Shore service The messages listed in Table 7 2 Operationa...

Page 38: ...ph 4 14 for information on setting up the Persistent Switch Heater Output 4 2 4 LED Annunciators There are five LED annunciators on the front panel that are used to indicate the status of the instrument These are to provide easy verification of the operation of the instrument Fault On when a hardware fault condition exists blinking when a soft fault condition exists Compliance On when output is in...

Page 39: ... setting selection and data entry for the majority of operator interface A few specialized keypad operations such as ramp segment entry are described in the individual operation paragraphs Direct Operation Key functions occur immediately when the key is pressed Zero Output Stop Output and Pause Output are examples of keys that operate this way Setting Selection Allows the user to select from a fin...

Page 40: ...he display mode Display Setup Select With Display Mode Current Use the s or t key to select the display mode either Current or Field Press Enter to accept the new selection and continue to the next setting screen Press Escape to cancel the new selection and return to the normal display 4 4 2 Display Remote Voltage Sense The Model 625 has the ability to display a remote voltage sense reading This c...

Page 41: ...pliance voltage The Ramping LED will be lit while the output current setting is ramping When the output current setting is entered it will be limited in magnitude by the maximum current setting Refer to Paragraph 4 11 to setup the maximum settings To change the output current setting when in current display mode press the Output Setting key The output current setting value on the normal display wi...

Page 42: ...to Paragraph 4 11 to setup maximum settings 4 6 CURRENT RAMP RATE The output current of the Model 625 will always ramp from one current setting to another There is no way to turn off the current ramping function but if a very fast ramp rate is desired a ramp rate as large as 99 999 A s can be entered to simulate a step change On most superconducting magnets the maximum rate at which it can be char...

Page 43: ...xes are described in Paragraph 4 5 4 9 STOP OUTPUT CURRENT The Stop Output key will stop the output current ramp within two seconds after the key is pressed even if the magnet is ramping against the compliance voltage A new output current setpoint must be entered for the output current to begin ramping again 4 10 PAUSE OUTPUT CURRENT The Pause Output key will pause the output current ramp within t...

Page 44: ...ress Max Settings then Enter until the following display setup screen appears as a prompt for the maximum compliance voltage limit Maximum Settings Enter a Value For Max Voltage 5 0000 V Use the data entry keys to enter the maximum compliance voltage limit value between 0 1000 and 5 0000 V Press Enter to accept the new value Press Escape to restart the setting sequence and enter a different value ...

Page 45: ...o the normal display If the ramp segments are enabled the next ramp segments screen that appears is for entering or editing the ramp segments table All five of the ramp segments are shown on the display at the same time The segments should be entered in order of increasing current An entry of 0 A will indicate the end of the table and the instrument will not search beyond that segment Ramp Segment...

Page 46: ...he normal display 4 13 2 Field Constant Value The field constant value can be entered in units of T A or kG A depending on what was chosen in the previous step The field constant value will be used to calculate the magnetic field To enter a value for the field constant continue from the field constant units screen or press Field Constant then Enter until the following display setup screen appears ...

Page 47: ...sabled the heater must be off If the heater is on warming or cooling then the persistent switch heater mode will not be allowed to change and an error box will pop up explaining why One of two boxes will show up both shown below Change not allowed while PSH is on Change not allowed while PSH is warming or cooling 4 14 2 Persistent Switch Heater Current Setting The next setting that is available fo...

Page 48: ...tween 5 and 100 seconds Press Enter to accept the new value Press Escape to restart the setting sequence and enter a different value Press Escape again to leave the setting sequence 4 14 4 Persistent Mode Ramp Rate A magnet is said to be in persistent mode when the persistent switch heater is off and the magnet is shorted by the persistent switch in its superconducting state While the magnet is in...

Page 49: ...ch heater press the PSH On key The PSH will begin warming and the PSH On LED will blink The output current of the power supply cannot be changed while the PSH is in transition Once the persistent switch has stabilized as determined by the PSH delay time the PSH will be on and the PSH On LED will be on solid Refer to Paragraph 4 14 3 to setup the PSH delay time Note that the PSH cannot be turned on...

Page 50: ...tly monitors the output current and calculates an actual current ramp rate If the current changes at a rate greater than the current step limit then a quench is detected The current step limit should be set to a value greater than any expected ramp rate 4 16 1 Quench Detection Enable Quench detection can be enabled or disabled If quench detection is disabled another form of quench detection should...

Page 51: ...wing example shows the description for the magnet quench error Magnet quench detected Current output set to 0 Normal operation will not be resumed until the magnet is completely discharged Press Status to attempt to clear error 4 18 EXTERNAL CURRENT PROGRAMMING The output current of the Model 625 can be set internally externally or by the sum of the external and internal settings Normally the curr...

Page 52: ...o Output Stop Output Pause Output PSH On and PSH Off This allows the power supply to be operated without allowing any changes to the power supply setup A 3 digit code must be used to lock and unlock the keypad The factory default code is 123 and it can only be changed using a computer interface If the instrument parameters are set to default values the code is reset to the factory default The inst...

Page 53: ...y The first computer interface screen appears as a prompt for Baud Computer Interface Select With Baud 9600 Use the s or t key to select 9600 19200 38400 or 57600 Baud Default is 9600 Baud Press Enter to accept the new selection and continue to the next screen Press Escape to cancel the new selection and return to the normal display 4 20 2 Changing IEEE 488 Interface Parameters Two interface param...

Page 54: ...4 1 Main Code Version 1 0 DAC Code Version 1 0 Select With Default Values No Use the s or t key to select Yes for default values and No to continue without changing the parameter values Press Enter to accept the new selection and return to the normal display Press Escape to cancel the new selection and return to the normal display Table 4 1 Default Parameter Values Output Settings Output Current 0...

Page 55: ...s data onto the bus to other devices A LISTENER receives data from other devices through the bus The BUS CONTROLLER designates to the devices on the bus which function to perform The Model 625 performs the functions of TALKER and LISTENER but cannot be a BUS CONTROLLER The BUS CONTROLLER is the digital computer which tells the Model 625 which functions to perform Below are Model 625 IEEE 488 inter...

Page 56: ...ars as a prompt for the IEEE 488 terminators Computer Interface Select With IEEE Term Cr Lf Use the s or t key to select one of the following terminators CR LF LF CR LF and EOI The default is Cr Lf Press Enter to accept the new selection and continue to the next setting screen Press Escape to cancel the new selection and return to the normal display 5 1 2 Remote Local Operation Normal operations f...

Page 57: ...n started either individually or as part of a group of devices SPE Serial Poll Enable and SPD Serial Poll Disable Serial polling accesses the Service Request Status Byte Register This status register contains important operational information from the unit requesting service The SPD command ends the polling sequence 5 1 3 2 Common Commands Common Commands are addressed commands which create common...

Page 58: ...2 Event Registers Each register set includes an event register as shown in Figure 5 1 Bits in the event register correspond to various system events and latch when the event occurs When an event bit is set subsequent events corresponding to that bit are ignored Set bits remain latched until the register is cleared by a query command such as ESR or a CLS command The register is read only 5 1 4 1 3 ...

Page 59: ...Lake Shore Model 625 Superconducting MPS User s Manual Computer Interface Operation 5 5 Figure 5 1 Model 625 Status System Sheet 1 of 2 ...

Page 60: ...Lake Shore Model 625 Superconducting MPS User s Manual 5 6 Computer Interface Operation Figure 5 1 Model 625 Status System Sheet 2 of 2 ...

Page 61: ... weighted sum of all bits in the register see Table 5 1 The actual commands are described later in this section 5 1 4 1 8 Clearing Registers The methods to clear each register are detailed below Table 5 2 Register Clear Methods Register Method Example Condition Registers None registers are not latched Event Registers Standard Event Status Register Operation Event Register Error Status Event Regist...

Page 62: ...cognized header unrecognized terminators or an unsupported command Execution Error EXE Bit 4 This bit is set if an execution error has been detected This occurs when the instrument is instructed to do something not within its capabilities Query Error QYE Bit 2 This bit indicated a query error It occurs rarely and involves loss of data because the output queue is full Operation Complete OPC Bit 0 W...

Page 63: ...lue of the three values associated with the Error Status Registers The Error Status Enable command ERSTE programs the enable register and the query command ERSTE reads it ERSTR reads and clears the Error Status Register The used bits of the Error Status Event Register are described as follows DAC Processor Not Responding DAC Bit 5 This bit is set to indicate that communication to the DAC processor...

Page 64: ...ollows Magnet Discharging Through Crowbar MDC Bit 6 This bit is set to indicate that the magnet is currently discharging through the crowbar This can happen due to a hardware error or a power loss Magnet Quench Detected QNCH Bit 5 This bit is set to indicate that a magnet quench has been detected Remote Inhibit Detected OCF Bit 4 This bit is set if the remote inhibit condition has been detected Te...

Page 65: ...ister is the third value of the three values associated with the Error Status Registers The Error Status Enable command ERSTE programs the enable register and the query command ERSTE reads it ERSTR reads and clears the Error Status Register The used bits of the Error Status Event Register are described as follows PSH Short PSS Bit 1 This bit is set if the persistent switch heater circuitry has det...

Page 66: ...the bit may be read with the STB query which returns the binary weighted sum of all bits in the Status Byte this is the MSS function of the bit Performing a serial poll will automatically clear the RQS function but not the MSS function A STB will read the status of the MSS bit along with all of the summary bits but also will not clear it To clear the MSS bit either clear the event register that se...

Page 67: ...ill not cause another SRQ unless the event register that caused the first SRQ has been cleared typically by a query of the event register The serial poll does not clear MSS The MSS bit stays set until all enabled Status Byte summary bits are cleared typically by a query of the associated event register refer to Paragraph 5 1 4 4 4 The programming example in Table 5 3 initiates an SRQ when a comman...

Page 68: ...ice operations complete However the commands operate with two distinct methods The OPC command is used in conjunction with bit 0 OPC of the Standard Event Status Register If OPC is sent as the last command in a command sequence bit 0 will be set when the instrument completes the operation that was initiated by the command sequence Additional commands may be sent between the instrument and the bus ...

Page 69: ...e Board Installation for Visual Basic Program This procedure works for Plug and Play GPIB Hardware and Software for Windows 98 95 This example uses the AT GPIB TNT GPIB card 1 Install the GPIB Plug and Play Software and Hardware using National Instruments instructions 2 Verify that the following files have been installed to the Windows System folder a gpib 32 dll b gpib dll c gpib32ft dll Files b ...

Page 70: ...Lake Shore Model 625 Superconducting MPS User s Manual 5 16 Computer Interface Operation Figure 5 8 GPIB0 Setting Configuration Figure 5 9 DEV 12 Device Template Configuration ...

Page 71: ...EE 488 Interface Program in Visual Basic 1 Start VB6 2 Choose Standard EXE and select Open 3 Resize form window to desired size 4 On the Project Menu select Add Module select the Existing tab then navigate to the location on your computer to add the following files Niglobal bas and Vbib 32 bas 5 Add controls to form a Add three Label controls to the form b Add two TextBox controls to the form c Ad...

Page 72: ...e Editor window under the Object dropdown list select General Add the statement Public gSend as Boolean b Double Click on cmdSend Add code segment under Private Sub cmdSend_Click as shown in Table 5 5 c In the Code Editor window under the Object dropdown list select Form Make sure the Procedure dropdown list is set at Load The Code window should have written the segment of code Private Sub Form_Lo...

Page 73: ...il gSend True Loop until Send button pressed gSend False Set Flag as False strCommand frmIEEE txtCommand Text Get Command strReturn Clear response display strCommand UCase strCommand Set all characters to upper case If strCommand EXIT Then Get out on EXIT End End If Call ibwrt intDevice strCommand term Send command to instrument If ibsta And EERR Then Check for IEEE errors do error handling if nee...

Page 74: ...s is 12 and terminators are CR LF 5 1 5 4 Quick Basic Program The IEEE 488 interface program in Table 5 6 works with QuickBasic 4 0 4 5 or Qbasic on an IBM PC or compatible running DOS or in a DOS window It assumes your IEEE 488 GPIB card is installed and operating correctly refer to Paragraph 5 1 5 3 Use the following procedure to develop the Serial Interface Program in Quick Basic 1 Copy c gpib ...

Page 75: ...Lake Shore Model 625 Superconducting MPS User s Manual Computer Interface Operation 5 21 IBCONF EXE eps Figure 5 10 Typical National Instruments GPIB Configuration from IBCONF EXE ...

Page 76: ... prompt The computer transmits to the instrument and displays any response If no query is sent the instrument responds to the last query received Type EXIT to exit the program REM INCLUDE c gpib pc qbasic qbdecl bas Link to IEEE calls CLS Clear screen PRINT IEEE 488 COMMUNICATION PROGRAM PRINT CALL IBFIND dev12 DEV12 Open communication at address 12 TERM CHR 13 CHR 10 Terminators are CR LF LOOP2 I...

Page 77: ...led query without a nothing will be returned Incorrectly spelled commands and queries are ignored Commands and queries should have a space separating the command and associated parameters Leading zeros and zeros following a decimal point are not needed in a command string but are sent in response to a query A leading is not required but a leading is required 5 1 6 Troubleshooting New Installation ...

Page 78: ...or connecting the instrument to computers with either 9 or 25 pin connectors Paragraph 7 12 1 gives the most common pin assignments for 9 and 25 pin connectors Please note that not all pins or functions are supported by the Model 625 The instrument serial connector is the plug half of a mating pair and must be matched with a socket on the cable If a cable has the correct wiring configuration but a...

Page 79: ... method of error detection One parity bit configured for odd parity is included in each character ASCII letter and number characters are used most often as character data Punctuation characters are used as delimiters to separate different commands or pieces of data Two special ASCII characters carriage return CR 0DH and line feed LF 0AH are used to indicate the end of a message string Table 5 7 Se...

Page 80: ...m When issuing commands only the user program should Properly format and transmit the command including terminators as one string Guarantee that no other communication is started for 50 ms after the last character is transmitted Not initiate communication more than 20 times per second When issuing queries or queries and commands together the user program should Properly format and transmit the que...

Page 81: ...to desired size 4 On the Project Menu click Components to bring up a list of additional controls available in VB6 5 Scroll through the controls and select Microsoft Comm Control 6 0 Select OK In the toolbar at the left of the screen the Comm Control will have appeared as a telephone icon 6 Select the Comm control and add it to the form 7 Add controls to form a Add three Label controls to the form ...

Page 82: ...atement Public gSend as Boolean b Double Click on cmdSend Add code segment under Private Sub cmdSend_Click as shown in Table 5 9 c In the Code Editor window under the Object dropdown list select Form Make sure the Procedure dropdown list is set at Load The Code window should have written the segment of code Private Sub Form_Load Add the code to this subroutine as shown in Table 5 9 d Double Click ...

Page 83: ...r events Loop Until gSend True Loop until Send button pressed gSend False Set Flag as false strCommand frmSerial txtCommand Text Get Command strReturn Clear response display strCommand UCase strCommand Set all characters to upper case If strCommand EXIT Then Get out on EXIT End End If frmSerial MSComm1 Output strCommand Term Send command to instrument If InStr strCommand 0 Then Check to see if que...

Page 84: ... Quick Basic Serial Interface Program CLS Clear screen PRINT SERIAL COMMUNICATION PROGRAM PRINT TIMEOUT 2000 Read timeout may need more BAUD 9600 TERM CHR 13 CHR 10 Terminators are CR LF OPEN COM1 BAUD O 7 1 RS FOR RANDOM AS 1 LEN 256 LOOP1 LINE INPUT ENTER COMMAND or EXIT CMD Get command from keyboard CMD UCASE CMD Change input to upper case IF CMD EXIT THEN CLOSE 1 END Get out on Exit CMD CMD TE...

Page 85: ...terface program If you enter a correctly spelled query without a nothing will be returned Incorrectly spelled commands and queries are ignored Commands and queries should have a space separating the command and associated parameters Leading zeros and zeros following a decimal point are not needed in a command string but are sent in response to a query A leading is not required but a leading is req...

Page 86: ...that may include a decimal point nnn nnnE nn Number represented in scientific notation format term Terminator characters Indicated a parameter field many are command specific state Parameter field with only On Off states NOTE Any number being represented in scientific notation may also be entered as a string of number characters If the number is only represented as a string of number characters it...

Page 87: ...ry 39 MODE IEEE Interface Mode Cmd 39 MODE IEEE Interface Mode Query 39 Command Function Page OPST Operational Status Query 39 OPSTE Operational Status Enable Cmd 39 OPSTE Operational Status Enable Query 39 OPSTR Operational Status Register Query 39 PSH Persistent Switch Heater Cmd 40 PSH Persistent Switch Heater Query 40 PSHIS Last Current Setting for PSH Query 40 PSHS Persistent Switch Parameter...

Page 88: ...e binary weighted sum of all bits in the register Refer to Paragraph 5 1 4 2 1 ESE Standard Event Status Enable Register Query Input ESE term Returned bit weighting term Format nnn Refer to command for description ESR Standard Event Status Register Query Input ESR term Returned bit weighting Format nnn Remarks Bits in this register correspond to various system events and latch when the event occur...

Page 89: ...ut RST term Remarks Sets controller parameters to power up settings Use the DFLT command to set factory defaults SRE Service Request Enable Register Command Input SRE bit weighting term Format nnn Remarks The Service Request Enable Register determines which summary bits of the Status Byte may set bit 6 RQS MSS of the Status Byte to generate a Service Request This command programs the enable regist...

Page 90: ...ion values to factory defaults and resets the instrument The instrument must be at zero amps for this command to work The 99 is included to prevent accidentally setting the unit to defaults DISP Display Parameter Command Input DISP mode volt sense brightness term Format n n n mode Specifies the display mode 0 Current 1 Field volt sense Specifies if the remote voltage sense reading is displayed 0 D...

Page 91: ...turned hardware errors operational errors PSH errors term Format nnn nnn nnn Refer to Paragraph 5 1 4 3 for a list of error bits ERSTR Error Status Register Query Input ERSTR term Returned hardware errors operational errors PSH errors term Format nnn nnn nnn Remarks The integers returned represent the sum of the bit weighting of the error bits These error bits are latched when an error condition i...

Page 92: ...turns keypad status since the last KEYST KEYST returns 1 after initial power up LIMIT Limit Output Settings Command Input LIMIT current voltage rate term Format nn nnnn n nnnn n nnnn current Specifies the maximum output current setting allowed 0 60 1000 A voltage Specifies the maximum compliance voltage setting allowed 0 1000 5 0000 V rate Specifies the maximum output current ramp rate setting all...

Page 93: ... Input OPSTE bit weighting term Format nnn Remarks Each bit has a bit weighting and represents the enable disable mask of the corresponding operational status bit in the Operational Status Register This determines which status bits can set the corresponding summary bit in the Status Byte Register To enable a status bit send the command OPSTE with the sum of the bit weighting for each desired bit R...

Page 94: ...this current is equal to the present output current or the heater is turned on using the PSH 99 command If 99 9999 is returned then the output current when the PSH was turned off last is unknown PSHS Persistent Switch Heater Parameter Command Input PSHS enable current delay term Format n nnn nnn term enable Specifies if there is a persistent switch in the system 0 Disabled no PSH 1 Enabled current...

Page 95: ... enable Specifies if the persistent mode ramp rate is to be used when the magnet is in persistent mode PSH heater off 0 Never use persistent mode ramp rate 1 Use persistent mode ramp rate when in persistent mode rate Specifies the ramp rate to use while in persistent mode 0 0001 99 999 A s Remarks Typically the current can be ramped faster when the magnet is in persistent mode since the current ch...

Page 96: ...the output current ramp rate based on the output current Ramp segments need to be setup first using the RSEGS command RSEG Ramp Segments Enable Query Input RSEG term Returned enable term Format n Refer to command for description RSEGS Ramp Segments Parameters Command Input RSEGS segment current rate term Format n nn nnnn n nnnn term segment Specifies the ramp segment to be modified 1 5 current Spe...

Page 97: ...e that the output will ramp to at the present ramp rate Setting value is limited by LIMIT SETI Output Current Setting Query Input SETI term Returned current term Format nn nnnn Refer to command for description SETV Output Compliance Voltage Setting Command Input SETV voltage term Format n nnnn voltage Specifies the output compliance voltage setting 0 1000 5 0000 V Remarks Sets the output complianc...

Page 98: ...ommand or the GET group execute trigger function to start a trigger over the interface TRIG Trigger Output Current Setting Query Input TRIG term Returned I value term Format nn nnnn Refer to command for description XPGM External Program Mode Command Input XPGM mode term Format n mode 0 Internal 1 External 2 Sum Example XPGM 1 term Places the Model 625 into external program mode where the output cu...

Page 99: ...220V EU CEE 7 7 4 240V EU CEE 7 7 5 240V UK BS 1363 6 240V Swiss SEV 1011 7 220V China GB 1002 6 2 ACCESSORIES INCLUDED Part Number Description 6271 Model 625 Superconducting MPS User s Manual 6241 Two front handles 6242 Two rear handles protectors 6243 Output shorting bar and terminal fasteners 6251 25 pin D sub mating connector digital I O 6252 15 pin D sub mating connector analog I O Calibratio...

Page 100: ...Lake Shore Model 625 Superconducting MPS User s Manual 6 2 Options and Accessories ...

Page 101: ...Lake Shore Model 625 Superconducting MPS User s Manual Options and Accessories 6 3 This Page Intentionally Left Blank ...

Page 102: ......

Page 103: ... ext 131 Sales Instrument Service Fax 614 818 1600 614 818 1609 Sales Instrument Service When contacting Lake Shore please provide your name and complete contact information including e mail address if possible It is often helpful to include the instrument model number and serial number located on the rear panel of the instrument as well as the firmware revision information as described in Paragra...

Page 104: ...Drawer 7 4 LINE VOLTAGE SELECTION Use the following procedure to change the instrument line voltage selector Verify the fuse value and drawer whenever the line voltage is changed WARNING To avoid potentially lethal shocks turn off the power supply and disconnect it from AC power before performing this procedure 1 Identify the line input assembly on the instrument rear panel See Figure 7 2 2 Turn t...

Page 105: ... a small screwdriver release the drawer holding the line voltage selector and fuses 5 Remove and discard both existing fuses Replace with proper Slow Blow time delay fuse ratings as follows 100 120 V 10 0 A T 250 V 0 25 1 25 220 240 V 5 0 A T 250 V 5 20 mm 6 Re assemble line input assembly in reverse order 7 Verify voltage indicator in the line input assembly window 8 Connect instrument power cord...

Page 106: ...prevent damage to the supply Table 7 2 Operational Errors Magnet Discharging Through Crowbar The magnet is currently discharging through the output crowbar SCR This error can be cleared when the magnet is completely discharged Magnet Quench Detected A magnet quench has been detected because the output current changed at a rate greater than the current step limit This error can be cleared when the ...

Page 107: ...ion the default setting send CALCOMP 0 over the interface To make the change nonvolatile send the CALSAVE command after setting the compensation or else the previous setting will be used at the next power up There are some magnet systems in which the 25 Ω output resistor is not necessary for stable operation Many of the magnets that have a persistent switch have enough resistance for the power sup...

Page 108: ...e container Use only plastic bags approved for storage of ESD material 6 Do not handle ESDS devices unnecessarily or remove from the packages until actually used or tested 7 9 ENCLOSURE BOTTOM REMOVAL AND REPLACEMENT WARNING To avoid potentially lethal shocks discharge the magnet turn off the power supply and disconnect it from AC power line before performing this procedure Only qualified personne...

Page 109: ...el and to avoid inducing an Electrostatic Discharge ESD into the device 3 Use IC puller to remove existing IC from the socket 4 Noting orientation of new IC use an IC insertion tool to place new device into socket Eprom eps 5 Follow the top of enclosure INSTALLATION procedure in Paragraph 7 9 7 11 PSH OUTPUT COMPLIANCE VOLTAGE CONFIGURATION The persistent switch heater output maximum compliance vo...

Page 110: ...Lake Shore Model 625 Superconducting MPS User s Manual 7 8 Service 625 PCB bmp Figure 7 3 Location Of Important Internal Components ...

Page 111: ...are defined in Figures 7 4 thru 7 8 Analog_Output bmp Pin Name Pin Name 1 2 3 4 5 6 7 8 Voltage Sense NC Current Program NC Voltage Monitor NC Current Monitor NC 9 10 11 12 13 14 15 Voltage Sense NC Current Program NC Voltage Monitor NC Current Monitor Figure 7 4 ANALOG I O Connector Details Heater Output bmp Pin Description Center Signal Shell Ground Figure 7 5 PSH OUTPUT Connector Details ...

Page 112: ...AL I O Connector Details RS 232_Connector bmp Model 625 Superconducting MPS Typical Computers DE 9P DTE DB 25P DTE DE 9P DTE Pin Description Pin Description Pin Description 1 No Connection 2 TD out 1 DCD in 2 Receive Data RD in 3 RD in 2 RD in 3 Transmit Data TD out 4 RTS out 3 TD out 4 Data Terminal Ready DTR out 5 CTS in 4 DTR out 5 Ground GND 6 DSR in 5 GND 6 Data Set Ready DSR in 7 GND 6 DSR i...

Page 113: ... 1 NC 7 RTS out 7 DTR tied to 4 8 CTS in 8 NC 1 DCD in Model 625 to PC Serial Interface PC with DB 25P Model 625 DE 9P Standard Null Modem Cable DE 9S to DB 25S PC DB 25P 5 GND 7 GND 2 RD in 2 TD out 3 TD out 3 RD in 1 NC 4 RTS out 7 DTR tied to 4 5 CTS in 8 NC 8 DCD in 6 DSR in 20 DTR out 4 DTR out 6 DSR in Model 625 to PC Interface using Null Modem Adapter Model 625 DE 9P Null Modem Adapter PC D...

Page 114: ...same time Figure 7 8 shows the IEEE 488 Interface connector pin location and signal names as viewed from the Model 625 rear panel IEEE Connector bmp PIN SYMBOL DESCRIPTION 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 DIO 1 DIO 2 DIO 3 DIO 4 EOI DAV NRFD NDAC IFC SRQ ATN SHIELD DIO 5 DIO 6 DIO 7 DIO 8 REN GND 6 GND 7 GND 8 GND 9 GND 10 GND 11 GND Data Input Output Line 1 Data Inpu...

Page 115: ...rface command data formatting and typical values If the old values are saved they can be reloaded in the case of accidental loss of data during calibration New calculated calibration coefficients should be very similar to the old values Discrepancy between the old and new values of more than 0 1 of gain calibration coefficients or 0 1 of range for zero coefficients could indicate an error in the c...

Page 116: ...l develop 5 W 3 PSH Resistor This is simply a 1 W 100 resistor used to develop a voltage from the PSH output current to drive the Analog Current Programming Input for its gain calibration During the procedure this resistor will dissipate only 0 25 W 4 DC Voltmeter DVM The voltmeter must measure VDC accurately to 10 s of µV if resolution to 10 s of mA from the Model 625 is to be assured The HP34401...

Page 117: ... upper right reading REMOTE I is the reading needed for this step 4 Calculate zero offset constant external programming voltage reading 5 Send CALZ 7 zero offset constant 6 Verify the Model 625 external programming voltage reading to be 0 0 0001 V 7 Send CALSAVE to write this calibration to non volatile memory 7 13 3 6 Calibrate Output Current Gain Span This calibration is the most difficult and m...

Page 118: ...culate and record Imin Vshunt Rshunt 19 Send CALG 10 100 To set the output current gain trim constant to maximum 20 Wait 10 Seconds 21 Measure the actual voltage across the shunt and record Vshunt 22 Calculate and record Imaxnegtrim Vshunt Rshunt 23 Send CALG 10 100 To set the output current gain trim constant to minimum 24 Wait 10 seconds 25 Measure the actual voltage across the shunt and record ...

Page 119: ...ns the compensation ON so that the reading reflects only the current going through the load by subtracting the current going through the resistor 2 Send CALG 0 1 To set the output current reading gain constant to 1 3 Set the Model 625 output current to 60 A Ramp rate 20 A s nominal 4 Wait 30 seconds 5 Measure the actual voltage across the shunt and record Vshunt 6 Calculate and record Imeasuredneg...

Page 120: ...or interface and record Vreadingpos 12 Calculate gain constant per Equation 4 Equation 4 13 Verify the gain factor to be 1 0 02 14 Send CALG 5 gain constant 15 Verify the Model 625 output voltage reading to match the actual output voltage within 0 0005 V 16 Set the Model 625 output current to 0 A 17 Send CALSAVE to write this calibration to non volatile memory 7 13 3 9 Calibrate Remote Voltage Sen...

Page 121: ...ng REMOTE I is the reading needed for this step 7 Calculate the gain constant per Equation 6 Equation 6 8 Verify the gain constant to be 1 0 02 9 Send CALG 7 constant 10 Verify the Model 625 external programming voltage reading to match the measured PSH output voltage within 0 0005 V 11 Send CALSAVE to write this calibration to non volatile memory 12 Turn off the PSH output 7 13 4 Calibration Spec...

Page 122: ...ALZ type value term Format nn nnnnnnn type Specifies the item to calibrate Valid entries are 0 Output Current Reading 1 Bias A Reading 2 Bias B Reading 3 CM Voltage Reading 4 Out Control Reading 5 Output Voltage Reading 6 Remote Voltage Reading 7 External Programming Voltage 8 Temperature 9 Raw Supply Voltage 10 Actual Output Current value Zero offset calibration constant value Remarks Items marke...

Page 123: ...tus 1 ampere The constant current that if maintained in two straight parallel conductors of infinite length of negligible circular cross section and placed one meter apart in a vacuum would produce between these conductors a force equal to 2 10 7 newton per meter of length 2 This is one of the base units of the SI ampere turn A MKS unit of magnetomotive force equal to the magnetomotive force aroun...

Page 124: ... This returned flux tends to decrease the net magnetic field strength internal to the sample yielding a true internal field Hint given by Hint Ha DM where M is the volume magnetization and D is the demagnetization factor D is dependent on the sample geometry and orientation with respect to the field deviation The difference between the actual value of a controlled variable and the desired value co...

Page 125: ...and an external magnetic field applied at right angles to the current Named for Edwin H Hall 1855 1938 an American physicist hertz Hz A unit of frequency equal to one cycle per second hysteresis The dependence of the state of a system on its previous history generally in the form of a lagging of a physical effect behind its cause 1 Also see magnetic hysteresis IEC International Electrotechnical Co...

Page 126: ...l properties A small highly magnetic sample can have exactly the same moment as a larger weakly magnetic sample see Magnetization Measured in SI units as A m2 and in cgs units as emu 1 emu 10 3 A m2 magnetic units Units used in measuring magnetic quantities Includes ampere turn gauss gilbert line of force maxwell oersted and unit magnetic pole magnetization M This is a material specific property d...

Page 127: ...rely mounted in an instrument rack The standard rack mount is 19 inches wide A full rack instrument requires the entire width of the rack Two half rack instruments fit horizontally in one rack width relief valve A type of pressure relief device which is designed to relieve excessive pressure and to reclose and reseal to prevent further flow of gas from the cylinder after reseating pressure has bee...

Page 128: ...ter Freezing point of water Absolute zero kelvin Celsius Fahrenheit 0 K 273 15 K 373 15 K 273 15 C 0 C 100 C 459 67 F 32 F 212 F Triple point of water 273 16 K To convert Kelvin to Celsius subtract 273 15 To convert Celsius to Fahrenheit multiply C by 1 8 then add 32 or F 1 8 C 32 To convert Fahrenheit to Celsius subtract 32 from F then divide by 1 8 or C F 32 1 8 temperature coefficient measureme...

Page 129: ...y density energy productk W erg cm3 10 1 J m3 Demagnetization factor D N dimensionless 1 4 dimensionless NOTES a Gaussian units and cgs emu are the same for magnetic properties The defining relation is B H 4 M b Multiply a number in Gaussian units by C to convert it to SI e g 1 G 10 4 T G 10 4 T c SI Système International d Unités has been adopted by the National Bureau of Standards Where two conv...

Page 130: ...7 10 15 J Hz 1 C 1 Josephson Frequency Voltage Ratio 2e h 483 5939 THz V 1 Quantum of Circulation h 2me h me 3 6369 10 4 J Hz 1 kg 1 7 2739 10 4 J Hz 1 C 1 Rydberg Constant R 1 0974 107 m 1 Proton Moment in Nuclear Magnetons µp µN 2 7928 Bohr Magneton µB eh 2me 9 2741 10 24 J T 1 Proton Gyromagnetic Ratio p 2 6752 108 s 1 T 1 Diamagnetic Shielding Factor Spherical H2O Sample 1 H2O 1 0000 Molar Mas...

Page 131: ... and isolated the gases will liquefy when properly cooled A quick comparison between LHe and LN2 is provided in Table C 1 Table C 1 Comparison of Liquid Helium and Liquid Nitrogen PROPERTY LIQUID HELIUM LIQUID NITROGEN Boiling Point 1 atm in K Thermal Conductivity Gas w cm K Latent Heat of Vaporization Btu liter Liquid Density pounds liter 4 2 0 083 2 4 0 275 77 0 013 152 0 78 C3 0 HANDLING CRYOGE...

Page 132: ...every effort to protect eyes and skin from accidental contact with liquid or the cold gas issuing from it Protect your eyes with full face shield or chemical splash goggles Safety glasses even with side shields are not adequate Always wear special cryogenic gloves Tempshield Cryo Gloves or equivalent when handling anything that is or may have been in contact with the liquid or cold gas or with col...

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