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Lake Shore Model 234/234D User’s Manual

5-4

Service

Figure 5-3. Model 234 PCB Details

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Summary of Contents for 234

Page 1: ...ww lakeshore com Fax 614 891 1392 Telephone 614 891 2243 Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics Inc No government or other contractual support 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 dis...

Page 2: ...state to state or province to province 7 To the extent allowed by applicable law the remedies in this warranty statement are your sole and exclusive remedies 8 Except to the extent prohibited by applicable law in no event will lake shore or any of its subsidiaries affiliates or suppliers be liable for direct special incidental consequential or other damages including lost profit lost data or downt...

Page 3: ...chniques 2 4 2 4 Sensor Measurement 2 4 2 4 1 CalCurve 2 5 2 5 Power Connections 2 5 3 OPERATION 3 1 3 0 General 3 1 3 1 PCB DIP Switch Settings 3 1 3 2 Output to Temperature Conversion 3 2 3 3 Output to Log R Conversion 3 3 4 REMOTE OPERATION 4 1 4 0 General 4 1 4 1 Serial Interface 4 1 4 1 1 Serial Interface Connections 4 1 4 1 2 Serial Interface Operation 4 2 4 1 3 QuickBasic Programming Consid...

Page 4: ...e Page 1 1 Typical Model 234 Front Panel 1 3 1 2 Model 234D Dimensions Front Panel 1 4 1 3 Model 2308 1 Enclosure Physical Dimensions 1 9 1 4 Model 2308 12 Case Physical Dimensions 1 10 2 1 Typical Model 234 to Sensor Connections 2 3 2 2 Typical Wall Plug In Power Supply 2 6 3 1 Model 234 DIP Switch S1 Settings 3 1 4 1 Serial I O RJ11 Connector Pin Definitions 4 1 4 2 Serial Interface Connections ...

Page 5: ...re Transmitter sends temperature data from its position near a sensor to a data acquisition channel or strip chart recorder A Model 234D also displays the temperature or resistance The Model 234 operates with Cernox Carbon Glass Germanium or other resistance temperature sensors The Lake Shore CGR Series Carbon Glass resistance temperature sensors are the best choice for a highly reproducible senso...

Page 6: ...band A 0 to 20 mA output is also available to convert output to a voltage scaled from zero A 500 ohm 0 02 output load resistor produces the maximum full scale output of 10 volts A serial interface operating at 9600 baud can be used for service purposes to read sensor resistance temperature and configuration install and review the CalCurve and calibrate the transmitter A single 5 VDC supply powers ...

Page 7: ... display is capable of 1 mK resolution but actual resolution is no better than the measurement resolution listed in Table 1 1 Place S1 Switch 7 to R closed to cause the display to read in ohms Ω Note the display shows R not log R present at the transmitter output in this configuration The maximum resistance resolution is shown below The resistance display is capable of these resolutions but the ac...

Page 8: ...Lake Shore Model 234 234D User s Manual 1 4 Introduction Figure 1 2 Model 234D Front Panel and Dimensions ...

Page 9: ...0 02 Ω K at 300 K Measurement Scales Excitation Resolution and Accuracy Sensor Excitation Accuracy Scale Resistance Ω Voltage mV Resolution Ω Rdg Ω 0 1 6 5 0 0003 0 5 0 0006 1 4 5 12 5 5 0 0001 0 1 0 0013 2 9 60 10 0 001 0 1 0 006 3 45 125 5 0 001 0 1 0 013 4 90 360 10 0 003 0 1 0 036 5 290 1 25 K 10 0 01 0 1 0 13 6 900 3 6 K 10 0 03 0 1 0 36 7 2 9 K 12 5 K 10 0 1 0 1 1 3 8 9 K 36 K 10 0 3 0 1 3 6...

Page 10: ...ge 2 0 200 K Range 4 75 325 K Range 6 4 20 mA Output I V OUT Switch in I Position Output Resolution Current 1 22 µA 0 006 of full scale Temperature Equivalence 0 10 K 0 8 mK 0 200 K 15 3 mK 0 20 K 1 5 mK 0 300 K 22 9 mK 0 100 K 7 6 mK 75 325 K 19 1 mK Output Electronic Accuracy Current 5 µA 0 025 of full scale Temperature Equivalence 0 10 K 3 1 mK 0 200 K 62 5 mK 0 20 K 6 2 mK 0 300 K 93 7 mK 0 10...

Page 11: ...ACE For full serial interface specifications see Table 4 1 Type RS 232C Electrical Format Serial Three Wire Connector RJ11 telephone type jack MECHANICAL Ambient temperature range 15 C to 35 C 59 F to 95 F Power requirement 5 0 25 VDC 500 mA 234 750 mA 234D 234 Size 12 8 cm 5 in high 18 5 cm 7 3 in deep 3 cm 1 2 in wide 234D Size 4 4 cm 1 7 in high 23 cm 9 in deep 14 cm 5 5 in wide 234 Mounting Eu...

Page 12: ...versal input comes with the case See Table 1 2 and Figure 1 5 See Paragraph 2 5 for further information on the built in power supply CAUTION The Model 2308 12 bus is designed to power multiple Model 234s and may not be used with standard VME cards Table 1 2 Model 2308 12 Case Specifications No of Card Slots 12 Size 45 cm 17 7 in wide 18 cm 7 in high 26 cm 10 3 in deep Weight 5 5 kilograms 12 pound...

Page 13: ...Lake Shore Model 234 234D User s Manual Introduction 1 9 Figure 1 3 Model 2308 1 Enclosure Physical Dimensions ...

Page 14: ...Lake Shore Model 234 234D User s Manual 1 10 Introduction Figure 1 4 Model 2308 12 Case Physical Dimensions ...

Page 15: ...er and insurance company and notify Lake Shore Notify Lake Shore immediately of any missing parts Lake Shore cannot be responsible for any missing parts unless notified within 60 days of shipment See the standard Lake Shore Warranty on the A Page immediately behind the title page 2 2 REPACKAGING FOR SHIPMENT To return the Model 120CS or accessories for repair or replacement obtain a Return Goods A...

Page 16: ...the sensor make sure there are no electrical shorts or current leakage paths between the leads or between the leads and ground If IMI 7031 varnish or epoxy is used it may soften varnish type lead insulations so that high resistance shunts appear between wires if sufficient time for curing is not allowed Slide Teflon spaghetti tubing over bare leads when the possibility of shorting exists Avoid put...

Page 17: ... 32 or 36 AWG These wires have a fairly low thermal conductivity yet electrical resistance is not large enough to create measurement problems Thermally anchor lead wires at several temperatures between room temperature and cryogenic temperatures to guarantee no heat conduction through the leads to the sensor 2 3 3 Four Lead Measurements Measure all sensors including both two lead and four lead dev...

Page 18: ...citation voltage of 5 mV or 10 mV across the sensor Multiple scale resistors see Paragraph 5 4 convert the resulting sensor current to voltage The scale resistor with the best measurement resolution is selected Once the proper scale is determined the voltage across the scale resistor is measured The excitation voltage is then reversed The new reading is combined with the previous reading to elimin...

Page 19: ...nsor resistance log of resistance and maximum temperature error comes with each CalCurve See Chapter 4 for Curve programming or verifying curve data via the serial interface 2 5 POWER CONNECTIONS A 5 VDC supply in the VME rack or an external power supply powers the Model 234 Regulate the voltage to within 0 25 VDC Each Model 234 draws up to 500 mA from the supply 750 mA for the Model 234D The exte...

Page 20: ...Lake Shore Model 234 234D User s Manual 2 6 Installation Figure 2 2 Typical Wall Plug In Power Supply ...

Page 21: ... driver to loosen the top and bottom most screws on the front panel of a Model 234 mounted in a Model 2308 1 or 12 enclosure or the back panel of a Model 234D Then see Figure 5 3 for location of Switch S1 If the optional CalCurve is present set the T R switch to T If CalCurve is not shipped with the unit the factory setting is R If operating in temperature enable the corresponding range number on ...

Page 22: ...RATURE CONVERSION Output current or voltage are directly proportional to the temperature reading For the 4 20 mA output the following formula converts output current to temperature where T temperature in kelvin IOUT output current in mA and A and B are constants from Table 3 1 depending on temperature For the 0 20 mA output using a 500 Ω resistor for 0 10 V this formula converts output voltage to ...

Page 23: ... the output current to resistance If the 0 10 V output is used with a 500 Ω 0 02 output load resistor the following formula is used to compute the voltage where VOUT is the voltage measured from the Model 234 Use the following formula to convert output voltage to resistance Example If the I V OUT switch is in the I position 4 20 mA out the output is 4 mA for the log R equal to 0 1 Ω and 20 mA for ...

Page 24: ...Lake Shore Model 234 234D User s Manual 3 4 Operation This Page Intentionally Left Blank ...

Page 25: ...Format Serial Three Wire Baud Rate 9600 Timing Format Asynchronous Bits per Character 1 Start 8 Data No Parity 1 Stop Parity Type None Voltage Levels EIA Terminators Carriage Return 0DH and Line Feed 0AH Connector RJ11 Modular Telephone Jack 4 1 1 Serial Interface Connections A standard 6 wire RJ 11 modular telephone jack is the serial interface connector see Figure 4 1 Lake Shore Model 2001 data ...

Page 26: ... character buffer until the carriage return CR line feed LF terminator sequence After receiving the terminators the Model 234 responds to a query if present and stores the new input parameters Queries result in output of the requested data immediately following the processing of the command and terminator sequence Communication is half duplex For example the command string TAG 234 1 sets the elect...

Page 27: ...milliseconds for Scale 0 Sending new parameters or data requests at a rate faster than 2 Hz or 1 Hz is not recommended 4 1 3 QuickBasic Programming Considerations When communicating with a unit using a QuickBasic program do not use the LINE INPUT statement to retrieve data from the unit The LINE INPUT statement reads all characters from a data file up to a carriage return CR and then skips over th...

Page 28: ...to be increased for computers running faster than 50 MHz CLS Clear screen PRINT SERIAL COMMUNICATION PROGRAM PRINT TIMEOUT 2000 Read timeout may need more BAUD 9600 BAUD rate TERM CHR 13 CHR 10 Terminators are CR LF OPEN COM1 BAUD N 8 1 RS FOR RANDOM AS 1 LEN 1024 LOOP1 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 G...

Page 29: ...surement Input DA0 Set Current Output To Zero DA4 Set Current Output To 4 mA DA20 Set Current Output To 20 mA ERASE Erase Curve LOGR Logarithm of Sensor Resistance Query OHMS Sensor Resistance Query RANGE Output Temperature Range Query SCALE Resistance Measurement Scale Query SID Program Curve Identification SID Curve Identification Query TAG Program Tag Identification TAG Tag Identification Query...

Page 30: ... is spaced every 0 1 and yyy yyy is 6 temperature digits to the 1 mK place Input is free field There must be no missing breakpoints from the lowest log value to the highest log value over the area of interest To program a curve breakpoint for a resistance of 1000 Ω at 4 202 K the command would be C3 0 4 202 C Curve Breakpoint Query Input C x xx Returned yyy yyy Remarks Queries the curve breakpoint...

Page 31: ...nsor curve Do this prior to entering a new curve If a new curve is entered without erasing the existing curve data conflicts could occur LOGR Log of Sensor Resistance Query Input LOGR Returned X XXXXXX Remarks Returns value with 1 digit above the decimal point and 6 digits below Returns SHORT if input resistance is less than 1 Ω Returns OPEN if input resistance 400 kΩ OHMS Sensor Resistance Query ...

Page 32: ...ram Tag Identification Input TAG XXXXXXXX Returned Nothing Remarks Programs the 8 character tag identification When the unit is not assigned a specific tag number the instrument serial number is entered as the tag identification TAG Tag Identification Query Input TAG Returned XXXXXXXX Remarks Queries the 8 character tag identification TEMP Temperature Query Input TEMP Returned XXX XXX Remarks Retu...

Page 33: ...otection circuitry installed in Model 234 all the above problems eventually cause the 1 A slow blow fuse to burn out After correcting the cause replace the blown fuse with identical size and type 5 1 2 Output Stops Before Reaching Upper Limit Normally caused by too high of a resistance from output monitoring device Absolute maximum acceptable resistance is 500 Ω Also verify that proper range DIP s...

Page 34: ...Model 234 The three front panel connectors are the 8 pin terminal block J3 RJ11 Serial I O connector J4 and the power connector J2 See Figure 5 1 The Serial I O Connector pins are defined in Figure 4 1 The rear connector J1 is for connecting to the VMEbus See Figure 5 2 Figure 5 1 Front Panel Connector Details ...

Page 35: ...PROM CAUTION Disconnect power to the instrument before performing this procedure 1 Disconnect instrument power cord or remove instrument from rack 2 Locate the curve EEPROM U4 Note orientation of existing EEPROM circular dot on the top of the device See Figure 5 4 3 Use an IC puller or small flat blade screwdriver to remove existing EEPROM from socket 4 Install new curve EEPROM Match the circular ...

Page 36: ...Lake Shore Model 234 234D User s Manual 5 4 Service Figure 5 3 Model 234 PCB Details ...

Page 37: ...2 2 V 7 2 9 k 12 5 kΩ 31 6 kΩ 10 mV 0 55 to 2 2 V 8 9 k 36 kΩ 100 kΩ 10 mV 0 55 to 2 2 V 9 29 k 300 kΩ 316 kΩ 10 mV 0 21 to 2 2 V Scale changing depends on the forward A D voltage reading The lower and upper range in resistance is approximately subject to variations in gains and offsets Note the sensor voltage continually switches between positive and negative values to obtain the forward and reve...

Page 38: ...itive 5V is on the sleeve the return in the center pin 3 The mating screw terminal to the Model 234 front panel signal connector 4 1 Ω 10 Ω 100 Ω 1 kΩ 10 kΩ and 100 kΩ 0 01 resistors to simulate the sensor for calibration 5 A 500 Ω 0 02 1 3W resistor to load the 4 20 mA output 5 4 2 Preparation and General Test 1 Function of the I V switch Position I switch 8 open of the I V switch is normal opera...

Page 39: ...rature Transmitter current source and input stage operate properly a Verify the 1 kΩ calibration resistor is connected to the screw terminal SENSOR I and SENSOR I and shorting wires connect SENSOR I to SENSOR V and SENSOR I to SENSOR V b Connect the DVM negative lead to OUT and positive lead to OUT of the Model 234 c Make sure that the I V to the V position closed and the T R switch to R closed d ...

Page 40: ...tput calibration is complete 2 Input Calibration a Make sure that the T R switch R position closed and the I V switch V position closed b Connect the DVM negative lead to OUT and positive lead to OUT Make sure that the 500 Ω load resistor is also connected to OUT and OUT terminals c Connect the 1 kΩ calibration resistor to the screw terminal SENSOR I and SENSOR I to simulate a sensor load to the M...

Page 41: ...ion Commands Model 234 calibration consists of output calibration and input calibration NOTE Allow about 30 minutes for the Model 234 Temperature Transmitter to warm up before continuing with calibration 1 Serial Interface Program a Connect the Serial Port of the computer to the transmitter via the RJ11 connector b Invoke QBASIC or QuickBasic c Enter the Model 234 program provided in Paragraph 4 1...

Page 42: ...o simulate a sensor load to the Model 234 Use a shorting wire to connect SENSOR I to SENSOR V and another shorting wire to connect SENSOR I to SENSOR V d Issue the CAL3 serial interface command Wait 10 seconds e Issue the LOGR query The transmitter should return 3 00000 00010 If it reads correctly proceed to the next step otherwise go back to step 4 Also monitor the output The output should read 1...

Page 43: ...d and the T R switch to R closed 3 Put the 1 kΩ resistor between screw terminal SENSOR I and SENSOR I and shorting wires connect SENSOR I to SENSOR V and SENSOR I to SENSOR V 4 The DVM should read 5 000 volts 1 mV 5 Remove the 1 kΩ from the SENSOR I and SENSOR I screw terminals The DVM should read zero volts 1 mV 6 Put a short circuit between the SENSOR I and SENSOR I screw terminals The DVM shoul...

Page 44: ...Lake Shore Model 234 234D User s Manual 5 12 Service This Page Intentionally Left Blank ...

Page 45: ...mount case with built in power supply for use with up to 12 Model 234s 6 2 OPTIONS Model Description Of Option 8001 234 Factory Installed CalCurve formerly known as Precision Option Allows instrument to use the calibration data to calculate and output current proportional to temperature Requires calibrated sensor 8002 234 Field Installed CalCurve Requires field installation of a new Curve EEPROM A...

Page 46: ... Supply 120 V 60 Hz power source 2007 22 Wall Plug in Power Supply 230 V 50 Hz power source 2308 BP VME rack blank panel MAN 234 Model 234 User s Manual 6 4 WIRES LSCI P N Description Of Cable 9001 005 Quad Twist Cryogenic Wire Two twisted pairs phosphor bronze wire 36 AWG 0 13 mm 0 005 inch diameter 9001 007 Quad Lead Cryogenic Wire Phosphor bronze wire flat 32 AWG 0 20 mm 0 008 inch diameter 900...

Page 47: ...re range low magnetic field induced errors and high resistance to ionizing radiation Germanium Resistance Temperature Sensors are recognized secondary standard thermometers and have been employed in the measurement of temperature from 0 05 K to 30 K for more than 30 years 6 6 SPECIAL EQUIPMENT There are a number of 4 20 mA displays available for use with the Model 234 Suggested manufacturers inclu...

Page 48: ...Lake Shore Model 234 234D User s Manual 6 4 Options Accessories This Page Intentionally Left Blank ...

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