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234 Manual - Lake Shore Cryotronics, Inc.

1. User s Manual Model 234 Temperature Transmitter and Model 234D Temperature Transmitter Monitor Includes Coverage for Model 2308 01 Benchtop Enclosure Model 2308 12 VMEbus Rackmount Case For Use With The Following Lake Shore Sensors Series CGR Carbon Glass Resistance Temperature Sensors Series CX CernoxTM Resistance Temperature Sensors Series GR 200 Germanium Resistance Temperature Sensors El LakeShore Lake Shore Cryotronics Inc 575 McCorkle Boulevard Westerville Ohio 43082 8888 USA E Mail Addresses sales lakeshore com service lakeshore com Visit Our Website www 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 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 Shore shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing performance or use of this material Rev 1 5 P N 119 026 13 August 2009 Lake Shore
2. 1 kQ 1 mQ 100 000 to 999 999 Q 1k 10 kQ 10 MQ 1000 00 to 9999 99 Q 10k 100 kQ 0 19 10000 0 to 99999 9 Q 100k 300 kQ 1Q 100000 to 399999 Q gt 400 kQ Open Model 234D front panel and dimensions appear in Figure 1 2 Introduction Lake Shore Model 234 234D User s Manual cl cm 5 38 in Rear Panel g 3 Model 234D d Top View O N N i Display Front Panel A il BBARREA 2 LO eQ O N dt LakeShore 234D Temperature Monitor i Model 234D Front View C 234 1 2 eps Figure 1 2 Model 234D Front Panel and Dimensions Introduction Lake Shore Model 234 234D User s Manual Table 1 1 Model 234 Specifications THERMOMETRY Number of Inputs One Measurement Type Four lead Differential Sensor Type Cernox Carbon Glass or Germanium Resistance Temperature Sensor Sensor Units Ohms Q Input Range 1 Q to 300 kQ Sensor Excitation Constant voltage pinned at 5 mV or 10 mV dependent on resistance range Update Rate 4 readings second 2 readings second on Scale 0 only CalCurve Storage 1 curve factory or field loaded into EEPROM via serial interface Example Lake Shore Sensor CGR 1 1000 with 1 4L calibration Temperature Range 1 4 K 325 K with CGR 1 1000 Standard Sensor Curve Requires Calibrated Sensor and CalCurve Typical Sensor Sensitivity 700 Q Kat4 2K 0 15 Q K at 77 K 24 Q K at 10 K 0 02 Q K at 300 K Measurement Scales Excitation R
3. TEMP UNITS Function Identification Query Reset Command Program Curve Breakpoint Curve Breakpoint Query Calibrate Resistance Measurement Input Set Current Output To Zero Set Current Output To 4 mA Set Current Output To 20 mA Erase Curve Logarithm of Sensor Resistance Query Sensor Resistance Query Output Temperature Range Query Resistance Measurement Scale Query Program Curve Identification Curve Identification Query Program Tag Identification Tag Identification Query Temperature Query Output Units Query An explanation of the command structure is shown below Command Name Syntax of user input Information returned in response to query Explanation of returned data Remote Operation Brief Description of Function UNITS Output Units Query Input UNITS Returned TorR Remarks Used to query the T R switch setting Lake Shore Model 234 234D User s Manual IDN Identification Query Input Returned Remarks Example RST Input Returned Remarks Cc Input Returned Remarks C Input Returned Remarks CAL Input Returned Remarks IDN Manufacturer model number 0 software date Identifies instrument model number and software level The 0 in the returned syntax is in place of the serial number LSCI MODEL234 0 031093 Reset Command RST Nothing Similar to turning the power off and back on again Program Curve Breakpoint C X XX YY
4. SENSOR l and SENSOR l and shorting wires connect SENSOR I to SENSOR V and SENSOR l to SENSOR V Connect the DVM negative lead to OUT and positive lead to OUT of the Model 234 Make sure that the I V to the V position closed and the T R switch to R closed The DVM should read near 5 volts which is 10 x log 1000 6 Remove the 1 kQ from the SENSOR l and SENSOR l screw terminals The DVM should read about 0 volts Put a short between the SENSOR I and SENSOR I screw terminals The DVM should read about 10 volts 5 4 3 Calibration Procedure Using Range Switches amp Pushbutton S2 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 Service 5 7 Lake Shore Model 234 234D User s Manual 1 Output Calibration a Use a shorting wire to connect SENSOR l to SENSOR V and another shorting wire to connect SENSOR l to SENSOR V Do not attach a sensor leave the input open b Make sure that the T R switch closed R position and the I V switch in the V position closed c Connect the DVM negative lead to OUT and positive lead to OUT Make sure that the 500 Q load resistor is also connected to OUT and OUT terminals d Adjust trimpot R38 OUTPUT OFFSET until the DVM reads zero 0 05 mV e Use a shorting wire to connect SENSOR l to SENSOR I This is a short
5. 0 02 25 PPM Resistor Output Compliance 10 V 500 Q maximum load Output Temperature Ranges 0 10 K Range 1 0 100 K Range 3 0 300 K Range 5 0 20 K Range 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 uA 0 006 of full scale Temperature Equivalence 0 10K 0 8 mK 0 200 K 15 3 mK 0 20K 1 5 mK 0 300 K 22 9 mK 0 100K 7 6 mK 75 325K 19 1 mK Output Electronic Accuracy Current 5 pA 0 025 of full scale Temperature Equivalence 0 10K 3 1 mK 0 200K 62 5 mK 0 20K 6 2 mK 0 300 K 93 7 mK 0 100K 31 2 mK 75 325K 78 1 mK Output Temperature Coefficient Current 2 uA C 0 01 C Temperature Equivalence 0 10K 1 mK C 0 200K 20 mK C 0 20K 2 mK C 0 300K 30 mK C 0 100K 10 mK C 75 325 K 25 mK C 0 20 mA Output I V OUT Switch in V Position 0 10 V Out with 500 Q 0 02 25 PPM Load Resistor Output Resolution Voltage 0 61 mV Temperature Equivalence 0 10K 0 6 mK 0 200 K 12 2 mK 0 20K 1 2 mK 0 300 K 18 3 mK 0 100K 6 1 mK 75 325K 15 2mK 1 6 Introduction Lake Shore Model 234 234D User s Manual Table 1 1 Model 234 Specifications Continued Output Electronic Accuracy Voltage 4 5 mV 0 025 of full scale 0 02 resistor accuracy Temperature Equivalence 0 10K 4 5 mK 0 200 K 90 0 mK 0 20K 9 0 mK 0 300K 135 0 mK 0 100K 45 0 mK 75 325K 112 5mK Output Temperature Coefficient Voltage 1
6. 100 kQ RANGE 6 8 3333 V The output is 10 log Cal Resistor 6 Calibration Using Serial Interface Calibration 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 o ao o Connect the Serial Port of the computer to the transmitter via the RJ11 connector Invoke QBASIC or QuickBasic Enter the Model 234 program provided in Paragraph 4 1 4 Run the program Issue a command to verify the program is running For example the IDN query to view the Model number and Software date 2 Output calibration using the DAO and DA20 Commands a b Connect the DVM negative lead to OUT and positive lead to OUT Verify the 500 Q load resistor is also connected to OUT and OUT terminals Issue the DAO serial interface command Output should be close to zero Service 5 9 f Lake Shore Model 234 234D User s Manual Adjust trimpot R38 OUTPUT OFFSET until the DVM reads zero 0 05 mV Issue the DA20 serial interface command The output should be near 10 volts Adjust trimpot R40 OUTPUT GAIN until the DVM reads 10 0000V 0 05 mV The output calibration is complete 3 Input calibration using the CALX commands a Make sure that the T R switch R position closed and the I V switch V position closed Connect the DVM negativ
7. 25 mV C 0 01 C 0 0025 C of load resistor Temperature Equivalence 0 10K 1 2mK C 0 200K 25 mK C 0 20K 2 5mK C 0 300K 36 mK C 0 100K 12 mK C 75 325K 30 mK C COMPUTER INTERFACE 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 Euroboard end panel and back plane Transmitter does not use electrical bus format only its physical shape and power supply NOTES 1 Product Specifications are subject to change without notice 2 Total system temperature accuracy in a given temperature range is the sum of the specifications given for input calibration and output Introduction 1 7 Lake Shore Model 234 234D User s Manual 1 3 MODEL 2308 1 ENCLOSURE DESCRIPTION The Model 2308 1 Single Enclosure Case holds one Model 234 see Figure 1 4 It is the same enclosure that houses the Model 234D 1 4 MODEL 2308 12 CASE DESCRIPTION The Model 2308 12 VMEbus Rackmount Case holds up to twelve Model 234 Temperature Transmitters A 5 VDC power supply with universal input comes with the case See Table 1 2 and Figure 1 5 S
8. High Temperature Cernox Quad Lead Quad Twist Rox SoftCal and Thermox are trademarks of Lake Shore Cryotronics Inc Teflon is a trademark of DuPont De Nemours Copyright 1993 1995 1997 1999 2003 04 and 2009 by Lake Shore Cryotronics Inc All rights reserved No portion of this manual may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without the express written permission of Lake Shore Lake Shore Model 234 234D User s Manual TABLE OF CONTENTS Chapter Paragraph Title Page 1 INTRODUCTION vice oico scscetesect ete necdatestcenpacctieesecedieesuduenstassenersepreneetes 1 1 1 0 Generali oil E dnone coe a limi 1 1 1 1 Model 234 General Description 1 1 1 2 Model 234D General Description 1 3 1 3 Model 2308 1 Enclosure Description 1 8 1 4 Model 2308 12 Case Description 1 8 2 INSTALLATION 2 0 Generali ee Sic SB ete Dl eh 2 1 Inspection and Unpacking i 2 2 Repackaging For Shipment 2 3 Sensor Installation Recommendations 2 2 2 3 1 Sensor Mounting i 2 2 2 3 2 Connecting Leads To The Sensor 2 3 2 3 3 Four Lead Measurements rr renen nens 2 3 2 3 4 Proper Shielding TEChNIQUES n 2 4 2 4 Sensor Measuremen
9. circuit for the sensor f Adjust trimpot R40 OUTPUT GAIN until the DVM reads 10 0000V 0 05 mV Output 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 Q load resistor is also connected to OUT and OUT terminals c Connect the 1 kQ calibration resistor to the screw terminal SENSOR l and SENSOR I to simulate a sensor load to the Model 234 Use a shorting wire to connect SENSOR l to SENSOR V and another shorting wire to connect SENSOR l to SENSOR V d Switch all of the RANGE to OPEN except RANGE 4 which is open to calibrate the input with the 1 KQ calibration resistor e Press the S2 pushbutton Wait 5 seconds The output should read 10 x log 1000 6 5 0000 volts If it does not read 5 0000 1 mV then press the S2 button again 5 8 Service 5 4 4 Lake Shore Model 234 234D User s Manual Repeat Steps c thru e for 1 Q 10 Q 100 Q 10 kQ and 100 kQ 0 01 calibration resistors For each resistor the RANGE switch to be closed is shown in the table below When all ranges have been calibrated the outputs should read as shown in the table below Input calibration is complete Output Calibration Range 1 mV Resistor Switch Closed 1Q RANGE 1 OV 10Q RANGE 2 1 6667 V 100 Q RANGE 3 3 3333 V 1kQ RANGE 4 5 0000 V 10 KQ RANGE 5 6 6667 V
10. implemented on the Model 234 Temperature Transmitter Approximate Internal Internal Sensor Reference Sensor AID Voltage Scale Resistance Resistance Voltage Reading 0 1 60 10Q 5 mV 0 15 to 1 0 V 1 4 5 12 50 100 Q 5 mV 0 8 to 2 2 V 2 9 602 100 Q 10 mV 0 35 to 2 2 V 3 45 1259 1kQ 5 mV 0 8 to 2 2 V 4 90 360 Q 1 ka 10 mv 0 55 to 2 2 V 5 290 1 25 ka 3 16 ka 10 mv 0 55 to 2 2 V 6 900 3 6 kQ 10 kQ 10 mv 0 55 to 2 2 V 7 2 9 k 12 5 ka 31 6 ka 10 mV 0 55 to 2 2 V 8 9 k 36 kQ 100 KQ 10 mV 0 55 to 2 2 V 9 29 k 300 kQ 316 kQ 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 reverse readings Thus the sensor and A D voltage cannot be read reliably with a DC voltmeter Calibration results in a forward A D reading of approximately 0 65 or 2 volts at the time of calibration See table below This allows for over ranging dependent on variation in gains and offsets The reference resistance and approximate A D voltages used for each value of calibration resistance is shown below Internal Calibration Reference Approximate Resistance Resistance A D Voltage 1Q 10 Q 1 0 V 10 Q 100 Q 2 0 V 100 Q 1 kQ 2 0 V 1 kQ 3 16 KQ 0 65 V 1 kQ 10 kQ 2 0 V 10 kQ 31 6 kQ 0 65 V 10 kQ 100 kQ 2 0 V 100 kQ 316 k
11. of the T R Switch Normal operation is with the T R in the T position switch 7 open where a CalCurve option is chosen to produce an output in temperature With the switch in the R position the output current is proportional to the logarithm base 10 of the resistance of the sensor In the R position the I V switch selects either 4 to 20 mA or 0 to 20 mA In the V position the output is between 0 and 20 mA with 0 mA for log R 0 and 20 MA for log R 6 With the I V switch in the I position the output is between 4 and 20 mA with 4 mA for log R 0 and 20 mA for log R 6 Service Lake Shore Model 234 234D User s Manual 3 Preparation a Connect the 1 kQ calibration resistor to the screw terminal SENSOR l and SENSOR l to simulate a sensor load to the Model 234 Use a shorting wire to connect SENSOR l to SENSOR V and another shorting wire to connect SENSOR l to SENSOR V Connect the 500 resistor to the screw terminal to simulate an output load to the Model 234 Use the OUT and OUT pins Set the T R switch 7 to the R position closed and the I V switch to the V closed position Power the Model 234 Temperature Transmitter with the 5 VDC power supply 4 General Input Test The following test steps are recommended prior to calibration to verify that the Model 234 Temperature Transmitter current source and input stage operate properly a Verify the 1 kQ calibration resistor is connected to the screw terminal
12. 241 4 2 eps Figure 4 2 Serial Interface Connections 4 1 2 Serial Interface Operation The host computer initiates serial interface link operation it transmits either a command or a query to the Model 234 The Model 234 stores the characters in a 16 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 electronic tag number of the unit to 234 1 The query TAG returns the electronic tag number of the unit 4 2 Remote Operation Lake Shore Model 234 234D User s Manual When programming a Model 234 from the serial interface consider the following e The serial interface transmission mode asynchronous half duplex format 10 bits per character 1 start 8 data no parity and 1 stop and baud rate 9600 are factory set as outlined in Paragraph 4 1 e End of string terminators are fixed at CR LF e At 9600 baud each character takes about 1 millisecond to transmit Some host computers DMA serial interface access Programs must allow for transmission time delay before looking for a query response The unit stores received characters in a 16 character buffer After receiving termin
13. 34 Options amp Accessories 6 1 Lake Shore Model 234 234D User s Manual 6 3 ACCESSORIES Modular Cable RJ 11 to RJ 11 4 6 m 14 ft long 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 9001 008 Quad Lead Cryogenic Wire Phosphor bronze wire flat 32 AWG 0 13 mm 0 005 inch diameter Any quality dual shield twisted pair wire for dewar to Model 234 connector 6 2 Options amp Accessories Lake Shore Model 234 234D User s Manual 6 5 SENSORS Description Of Sensor Series CGR Carbon Glass Resistance Temperature Sensors is a highly reproducible sensor that can be used from 1 0 K to 100 K and above in magnetic fields up to 19 tesla Cernox Thin Film Resistance Temperature Sensors Series CX offer a negative temperature coefficient monotonic response over a wide temperature range low magnetic field induced errors and high resistance to ionizing radiation Germanium Resistance Temperature Sensors are recognized secondary standard thermometers and have Series GR 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 manuf
14. If the 0 10 V output is used with a 500 Q 0 02 output load resistor the following formula is used to compute the voltage yV log R out 10x where Vour is the voltage measured from the Model 234 Use the following formula to convert output voltage to resistance R 100 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 Q and 20 mA for the log R equal to 6 1 MQ A resistance of 1 KQ results in an output of 12 mA log R equal to 3 If input resistance is greater than 400 kQ output is 0 current A resistance greater than 400 kQ is considered an open and 0 current is used as an alarm indication for a 4 20 mA loop If the I V OUT switch is in the V position 0 20 mA out output is 0 mA for the log R equal to 0 1 Q and 20 MA for the log R equal to 6 1 MQ A resistance of 1 KQ results in an output of 10 mA log R 3 Operation 3 3 Lake Shore Model 234 234D User s Manual This Page Intentionally Left Blank Operation Lake Shore Model 234 234D User s Manual CHAPTER 4 REMOTE OPERATION 4 0 GENERAL This chapter covers the Serial Interface in Paragraph 4 1 and Serial Interface Commands in Paragraph 4 2 4 1 SERIAL INTERFACE The Model 234 has a serial interface for communications with a host computer It is an unbalanced single ended non terminated line used over short distances typically 10 feet or less The Model 234 serial int
15. Model 234 234D User s Manual LIMITED WARRANTY STATEMENT WARRANTY PERIOD ONE 1 YEAR 1 Lake Shore warrants that this Lake Shore product the Product will be free from defects in materials and workmanship for the Warranty Period specified above the Warranty Period If Lake Shore receives notice of any such defects during the Warranty Period and the Product is shipped freight prepaid Lake Shore will at its option either repair or replace the Product if it is so defective without charge to the owner for parts service labor or associated customary return shipping cost Any such replacement for the Product may be either new or equivalent in performance to new Replacement or repaired parts will be warranted for only the unexpired portion of the original warranty or 90 days whichever is greater 2 Lake Shore warrants the Product only if it has been sold by an authorized Lake Shore employee sales representative dealer or original equipment manufacturer OEM 3 The Product may contain remanufactured parts equivalent to new in performance or may have been subject to incidental use 4 The Warranty Period begins on the date of delivery of the Product or later on the date of installation of the Product if the Product is installed by Lake Shore provided that if you schedule or delay the Lake Shore installation for more than 30 days after delivery the Warranty Period begins on the 31st day after delivery 5 This limited warranty
16. Q 0 65 V Service 5 5 Lake Shore Model 234 234D User s Manual The table below indicates the serial command or Range Switch used in calibration When the transmitter is calibrated with the Serial Computer Port use the serial command shown in the table When the Calibration Switch S2 is used then the Range Switch shown must be selected Internal Serial Range Calibration Reference Command Switch Resistance Resistor s CALO 1 1Q 10Q CAL1 2 100 100 Q CAL2 3 100 Q 1 kQ CAL3 4 1 KQ 3 16 k210 kQ CAL4 5 10 kQ 31 6 k2100 kQ CAL5 6 100 kQ 316 KQ 5 4 1 Required Equipment for Calibration 1 5 A digital voltmeter DVM that measures DC voltage of 10 mV and 10 volts accurately to 0 005 A regulated 5 VDC power supply with tolerance within 0 25V capable of sourcing 500 mA on an S 760 or S 765 Switchcraft or equivalent power plug 0 218 inch outside diameter accepts 0 08 inch diameter pin The positive 5V is on the sleeve the return in the center pin The mating screw terminal to the Model 234 front panel signal connector 1 Q 10 Q 100 Q 1 KQ 10 KQ and 100 kQ 0 01 resistors to simulate the sensor for calibration A 500 Q 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 operation with the output 4 to 20 mA In position V switch 8 closed the output current is between 0 and 20 mA Function
17. Service in the United States or from the authorized sales service representative from which the product was purchased Instruments may not be accepted without a RGA number When returning an instrument for service Lake Shore must have the following information before attempting any repair Instrument model and serial number User name company address and phone number Malfunction symptoms Description of system Returned Goods Authorization RGA number Stio 35 Repack the system in its original container if available Affix shipping labels and FRAGILE warnings Write RGA number on the outside of the container or on the packing slip If not available consult Lake Shore for shipping and packing instructions Installation 2 1 Lake Shore Model 234 234D User s Manual 2 3 SENSOR INSTALLATION RECOMMENDATIONS See the Lake Shore Product Catalog for installation details and sensor specifications Call Lake Shore for copies of application notes or sensor installation questions 1 Do not ground the sensor 2 Shield leads and connect shield wire to SHIELD on screw terminal connector only Do not connect shield at other end of cable 3 Keep leads as short as possible 4 Use twisted pair wire Use Lake Shore Duo Twist wire or equivalent for two wire or Quad Twist wire or equivalent for four wire applications 5 Thermally anchor lead wires 2 3 1 Sensor Mounting Before installing the carbon glass or Germ
18. Y YYY Nothing Programs the curve breakpoint where x xx is log R uniformly spaced over three regions log R of 0 to 2 98 is spaced every 0 02 log R of 3 0 to 3 96 is spaced every 0 04 and log R of 4 0 to 5 6 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 Q at 4 202 K the command would be c3 0 4 202 Curve Breakpoint Query C x xx YYY YYY Queries the curve breakpoint for log R of x xx Returns temperature in a fixed field with 3 digits above and below the decimal point If no data is present for the log value returns 7 dashes e a Calibrate Resistance Measurement Input CALO CAL1 CAL2 CAL3 CAL4 or CAL5 Nothing Calibrates input scale for the calibration resistor attached to the input in place of the sensor Allow 10 seconds for calibration to be completed CALO 1Q CAL3 1kQ CAL1 10 Q CAL4 10 kQ CAL2 100 Q CAL5 100 kQ Remote Operation DAO Input Returned Remarks DA4 Input Returned Remarks DA20 Input Returned Remarks ERASE Input Returned Remarks LOGR Input Returned Remarks OHMS Input Returned Remarks RANGE Input Returned Remarks Lake Shore Model 234 234D User s Manual Set Current Output to Zero DAO Nothing Holds cur
19. acturers include the following Acculex 440 Myles Standish Blvd Taunton MA 02780 508 880 3660 Newport Electronics Inc 630 East Young Street Santa Ana CA 92705 5687 714 540 4914 Triplett Corp One Triplett Drive Bluffton OH 45817 1 800 874 7538 Options amp Accessories 6 3 Lake Shore Model 234 234D User s Manual This Page Intentionally Left Blank Options amp Accessories ow NOTES Lake Shore is a technology leader in the development of cryogenic temperature sensors precision low temperature measurement and control instrumentation and magnetic measurement and test systems Since 1968 Lake Shore physicists material scientists and engineers have dedicated themselves to the development of tomorrow s technology today Lake Shore serves a worldwide network of Customers including university and national laboratories aerospace and other industries as well as many of the premier companies around the world
20. anium sensor identify the leads as shown Be sure lead identification remains clear even after sensor installation Record the sensor serial number and location Looking Bess Black at epoxy When installing 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 putting stress on the device leads and allow for thermal contractions that occur during cooling which could fracture a solder joint or lead if installed under tension at room temperature For temporary mounting in cold temperature applications apply a thin layer of Apiezon N Grease between the sensor and sample to enhance thermal contact under slight pressure CAUTION Lake Shore will not warranty replace any device damaged by user designed clamps or solder mounting For semi permanent mountings use Stycast epoxy instead of Apiezon N Grease In all cases periodically inspect the sensor mounting to verify good thermal contact to the mounting surface is maintained 2 2 Installation Lake Shore Model 234 234D User s Manual 2 3 2 CONNECTING LEADS TO THE SENSOR Excessive heat flow through connecting leads to any temperatur
21. ators the unit responds to a query if requested and stores any new parameters The unit requires about 50 milliseconds to store new parameters before it can receive any new commands it requires 3 seconds for curve parameters and 10 seconds for input calibration The second command string of multiple command strings sent less than 50 milliseconds or 3 seconds or 10 seconds apart is ignored or returns a unpredictable response e The unit implements new parameters and updates measurement data internally once per 250 millisecond operation cycle 500 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 the carriage return line feed CR LF sequence The LINE INPUT statement does not work this way for the communications port It reads characters up to the CR and continues program operation while the unit transmits the LF In most cases the LF remains as the first character of the next input This could cause communications contention problems The QuickBasic 4 5 manual Section 3 5 2 Communications through the Serial Port reads Since every character is potentially significant da
22. 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 O Loosen top and bottom screws to gain access to D the 234 PCB 34 Temperature Transmitter O O O O O O O O OUT OUT SHIELD SENS I SENS V SHIELD SENS V SENS l SERIAL 1 0 5 VDC a Instrument Front View PCB Side View C 234 5 1 eps Figure 5 1 Front Panel Connector Details 5 2 Service Lake Shore Model 234 234D User s Manual J1 VMEbus Connector End View 60000000000000000000000 00000000C 0000090000000000000000000000000000 B 000000000000808608000008000 00 00 0 A 32 31 30 29 28 27 26 25 24 23 22 21 2019 1817 16 15 1413 1211 10 9 87 6 5 4 3 Pin Used O Pin Not Used Entire Row B is not present C 234 5 2 eps Not Used Not Used GND Entire Row GND Not Used Not Present Not Used GND Not Used Not Used Not Used GND Not Used Not Used Not Used GND Not Used Not Used Not Used GND Not Used Not Used Not Used 5 VDC 5 VDC Figure 5 2 VMEbus Connector Details 5 3 CALCURVE FIELD INSTALLATION The Model 8001 234 CalCurve is stored in an Electrically Erasable Programmable Read Only Memory EEPROM Use the following procedure to install or replace the CalCurve EEPROM CAUTION Disconnect power to the instru
23. does not apply to defects in the Product resulting from a improper or inadequate maintenance repair or calibration b fuses software and non rechargeable batteries c software interfacing parts or other supplies not furnished by Lake Shore d unauthorized modification or misuse e operation outside of the published specifications or f improper site preparation or maintenance 6 To the extent allowed by applicable law the above warranties are exclusive and no other warranty or condition whether written or oral is expressed or implied Lake shore specifically disclaims any implied warranties or conditions of merchantability satisfactory quality and or fitness for a particular purpose with respect to the product Some countries states or provinces do not allow limitations on an implied warranty so the above limitation or exclusion might not apply to you This warranty gives you specific legal rights and you might also have other rights that vary from country to country 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 downtime costs arising out of the use inability to use or result of
24. e lead to OUT and positive lead to OUT Make sure that the 500 Q load resistor is also connected to OUT and OUT terminals Connect the 1 kQ calibration resistor to the screw terminal SENSOR l and SENSOR I to simulate a sensor load to the Model 234 Use a shorting wire to connect SENSOR l to SENSOR V and another shorting wire to connect SENSOR I to SENSOR V Issue the CAL3 serial interface command Wait 10 seconds 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 10 log 1000 6 5 0000 volts Repeat Steps c thru e for 1 Q 10 Q 100 Q 10 KQ and 100 kQ 0 01 calibration resistors For each resistor the serial interface command to issue is shown in the table below When all ranges have been calibrated the outputs should read as shown in the table Input calibration is complete Calibration Serial Output Resistor Command 1 mV 1Q CALO OV 10 2 CAL1 1 6667 V 100 Q CAL2 3 3333 V 1 ka CAL3 5 0000 V 10 kQ CAL4 6 6667 V 100 kQ CAL5 8 3333 V Service Lake Shore Model 234 234D User s Manual 5 4 5 Calibration Verification 1 Connect the DVM negative lead to OUT and positive lead to OUT Make sure that the 500 Q load resistor is also connected to OUT and OUT terminals Make sure that the I V to the V position closed and the T R switch to R closed Put t
25. e sensor may differ the temperature between the active sensing element and the sample to which the sensor mounts This reflects as a real temperature offset between what is measured and the true sample temperature Eliminate such temperature errors with proper selection and installation of connecting leads To minimize heat flow through the leads select leads of small diameter and low thermal conductivity Phosphor bronze or Manganin wire is commonly used in sizes 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 devices in a four lead configuration to eliminate the effects of lead resistance The exact point at which the connecting leads solder to the two lead sensor normally results in a negligible temperature uncertainty Always use the four lead measurement configuration with Series CGR Carbon Glass and Series GR Germanium Resistance Temperature Sensors attached to the Model 234 OUT OUT pete Cas See eh Sk SHIELD a White SENS I I I I Yellow SENS V SHIELD dd V Green SENS SENS l C 234 2 1 eps Figure 2 1 Typ
26. ee 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 x 18 cm 7 in high x 26 cm 10 3 in deep Weight 5 5 kilograms 12 pounds Output Voltage 5 VDC 100 mV Peak to Peak Ripple Output Current 6 amperes maximum Input Power Universal 85 to 265 VAC 47 to 440 Hz 60 Watts Ambient Temp Range 15 to 35 C 59 to 95 F 1 8 Introduction Lake Shore Model 234 234D User s Manual 13 6 cm 5 38 in Blank Rear Panel Model 234 Top View D 00 Q E O Tn N N Front Panel Model 234 in a Model 2308 1 Enclosure Front View C 234 1 3 eps Figure 1 3 Model 2308 1 Enclosure Physical Dimensions Introduction Lake Shore Model 234 234D User s Manual TOP VIEW 000000000000000000000000000000000000000000000000000 FFFFFFFF F Fo o Lal Ea 00000000 44 9 cm 17 67 inches Wide FRONT VIEW A 17 7 cm 6 97 inches High mi i 26 1 cm gt _ SIDE VIEW 10 28 inches Deep C 234 1 4 eps Fig
27. ement scale Program Curve Identification SID XXXXXXXX Nothing Programs the 8 character curve identification When an optional CalCurve is stored the sensor serial number is usually entered as the curve identification Curve Identification Query SID X XXXXXXX Queries the 8 character curve identification Program Tag Identification TAG XXXXXXXX Nothing 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 Identification Query TAG XXXXXXXX Queries the 8 character tag identification Temperature Query TEMP XXX XXX Returns fixed field value with 3 digits above and below the decimal point Returns SHORT if input resistance is less than 1 Q Returns OPEN if input resistance gt 400 kQ Returns LOGR ON if the T R switch is in the R position Output Units Query UNITS TorR Queries T R switch setting T Temperature R Resistance Remote Operation Lake Shore Model 234 234D User s Manual CHAPTER 5 SERVICE 5 0 GENERAL This chapter covers General Troubleshooting in Paragraph 5 1 Model 234 Connectors in Paragraph 5 2 CalCurve Field Installation in Paragraph 5 3 and Calibration in Paragraph 5 4 5 1 GENERAL TROUBLESHOOTING 5 1 1 No Output On Board LED Off Verify output of external power supply is 5 VDC If not replace the supply If using the front panel input jack J2 v
28. erface complies with the electrical format of the RS 232C Interface Standard Table 4 1 Serial Interface Specifications Type RS 232C Electrical 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 type cables which maintain pin 1 polarity simplify interconnection Lake Shore offers the Model 2002 RJ 11 to DB 25 adapter and Model 2003 RJ 11 to DE 9 adapter for connecting to the host computer See Figure 4 2 Serial 1 0 PIN DESCRIPTION No Connection Serial In RxD 2 3 4 5 6 1 Serial Ground Serial Ground Serial Out TxD No Connection Figure 4 1 Serial I O RJ11 Connector Pin Definitions Remote Operation 4 1 Lake Shore Model 234 234D User s Manual LSCI Model 2002 RJ11 to DB25 Adapter SERIAL vo To Customer Supplied Computer DB25 Serial Interface Connector Use whichever adapter that matches your computer serial interface connector LSCI Model 2001 RJ11 gt Cable Assembly To Customer Supplied Computer DB9 Serial Interface Connector LSCI Model 2003 RJ11 to DB9 Adapter C
29. erify center post of connector coming from power supply is NEGATIVE If not correct wiring If using front panel input jack J2 verify external power supply is regulated at 5 VDC and can supply a minimum of 500 mA Also verify that OUT and SHIELD are not connected to each other Due to extensive protection 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 Q Also verify that proper range DIP switch is selected 5 1 3 Resistance Readings Are Incorrect Verify correct voltage and current connections to the sensor Parasitic resistances between the voltage and current connections inside the device can make the resistance measurement incorrect if the leads are connected incorrectly 5 1 4 Open Condition A sensor must be connected when power is applied If not an Open error will be displayed even if a sensor is re connected A power cycle must be performed with the sensor properly connected before the error will be cleared Service 5 1 Lake Shore Model 234 234D User s Manual 5 2 MODEL 234 CONNECTORS There are four connectors on the Model 234 The three front panel connectors are the 8 pin terminal block J3 RJ11 Serial I O
30. esolution and Accuracy Sensor Excitation Accuracy Scale Resistance Q Voltage mV Resolution Q Rdg Q 5 0 0003 0 5 0 0006 5 i 0 1 0 0013 10 0 1 0 006 5 i 0 1 0 013 10 t 0 1 0 036 10 0 1 0 13 10 0 1 0 36 10 0 1 1 3 10 0 1 3 6 29 K 300 K 10 i 0 5 30 Measurement Resolution Temperature Equivalence 0 04 mK at4 2K 6 6 mK at 77 K 0 12 mK at 30 K 67 mK at 300 K Electronic Measurement Equivalence Temperature Accuracy 2 mK at 4 2 K 18 mK at 77 K 8 mK at 10 K 1 2 K at 300 K Measurement Temperature Coefficient Measurement Units 0 0125 of resistance reading per C Temperature Equivalence 0 18 mK C at 4 2 K 0 126 Q 18 mK C at 77 35 K 0 0027 Q 0 8 mK C at 10 K 0 0185 Q 100 mK C at 300 K 0 0015 Q Typical Sensor Calibration Accuracy 4 mK at 4 2 K 45 mK at 77 35 K 4 mK at 10K 250 mK at 300 K 0 1 2 3 4 5 6 7 8 9 Introduction 1 5 Lake Shore Model 234 234D User s Manual Table 1 1 Model 234 Specifications Continued Typical CalCurve Target Accuracy 1 mK below 10 K 100 mK 40 K 100 K 5 mK 10 K 20K 1 K above 100 K 25 mK 20 K 40 K Magnetic Field Use Carbon Glass T gt 2 K and B lt 19 T Cernox Recommended Germanium Not Recommended OUTPUT Number of Outputs One Output Type Current source isolated from power source Output or sensor can be grounded but not both Output Range 4 20 mA or 0 20 mA for 0 10 V with 500 Q
31. for Temperature in K 3 2 4 1 Serial Interface Specifications ennen nen renerne 4 1 ii Table of Contents LIST OF ILLUSTRATIONS Lake Shore Model 234 234D User s Manual CHAPTER 1 INTRODUCTION 1 0 GENERAL The Model 234 is designed and manufactured in the USA by Lake Shore Cryotronics Inc In general references to the Model 234 applies to both the Model 234 Transmitter and 234D Transmitter Monitor Specific references are made where appropriate This chapter provides a General Description of the Model 234 in Paragraph 1 1 Model 234D General Description in Paragraph 1 2 Model 2308 1 Enclosure Description in Paragraph 1 3 and Model 2308 12 Case Description in Paragraph 1 4 We welcome comments on this manual Although we try to keep it error free some may occur To report an error describe it briefly and include the appropriate paragraph figure table and page number Send comments to Lake Shore Cryotronics Attn Technical Publications 575 McCorkle Blvd Westerville Ohio 43082 8888 This manual is subject to change without notice 1 1 MODEL 234 GENERAL DESCRIPTION The Model 234 Temperature 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 Sh
32. gure 3 1 Select only one range at a time The range is enabled when the switch is closed ON Units ship from the factory with the DIP switch set to RANGE1 closed 0 to 10 K OFF ON RANGE1 0 10 K RANGE2 0 20K RANGE4 0 200 K RANGE2 RANGE5 0 300 K RANGE3 RANGE6 75 325 K RANGE switch open range off RANGE4 closed range on RANGE5 Only active range should be selected RANGE6 T R switch open Temperature closed log R TER If T R is closed the 234D will WW OUT transmit log R but display R I OUT switch open 4 20 mA closed 0 20 mA C 234 3 1 eps Figure 3 1 Model 234 DIP Switch S1 Settings Operation 3 1 Lake Shore Model 234 234D User s Manual PCB DIP Switch Settings Continued Current Voltage I V OUT is for selection of proper output type Open is for 4 20 MA and closed is for 0 20 mA The 4 20 M is an industry standard while the 0 20 mA translates output into voltage scaled up to 10 V Fora 0 10 V output use a 500 2 0 02 output load resistor across the OUT and OUT terminals Load resistors less than 500 Q can convert the output to voltage using the following formula Toy mA Q out 1000 x B l Unless otherwise specified units ship from the factory with the DIP switch set with I V OUT open 4 20 mA 3 2 OUTPUT TO TEMPERATURE CONVERSION Output current or voltage are directly proportional to the temperature reading For the 4 20 mA output the following formu
33. h one of two enclosures a Model 2308 1 single space enclosure included with the Model 234D or Model 2308 12 rackmount case that holds 12 units See Figure 1 1 and Tables 1 1 and 1 2 1 2 Introduction Lake Shore Model 234 234D User s Manual 1 2 MODEL 234D GENERAL DESCRIPTION In addition to Model 234 features the Model 234D also provides local display of the temperature or resistance of a single sensor via a 6 digit LED Display It maintains full transmitter capabilities serial interface commands and curve format of the standard Model 234 The display is updated at one half the rate of the transmitter output Choose to display temperature in kelvin K or resistance in ohms Q by placing DIP switch S1 see Figure 5 3 switch 7 to T open for temperature or R closed for resistance The temperature 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 Q 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 actual resolution is not better than the measurement resolution listed in Table 1 1 Range Display Resolution Display 0 12 _ Short 1 10Q 0 01 MQ 1 00000 to 9 99999 Q 10 100Q 0 1 MQ 10 0000 to 99 9999 Q 100
34. he 1 KQ resistor between screw terminal SENSOR l and SENSOR l and shorting wires connect SENSOR I to SENSOR V and SENSOR l to SENSOR V The DVM should read 5 000 volts 1 mV 5 Remove the 1 kQ from the SENSOR I and SENSOR I screw terminals The DVM should read zero volts 1 mV Put a short circuit between the SENSOR l and SENSOR l screw terminals The DVM should read 10 000 volts 1 mV This concludes the Calibration Verification procedure Service 5 14 Lake Shore Model 234 234D User s Manual This Page Intentionally Left Blank Service Lake Shore Model 234 234D User s Manual CHAPTER 6 OPTIONS AND ACCESSORIES 6 0 GENERAL This chapter lists Model 234 enclosures options accessories sensors wires and special equipment 6 1 ENCLOSURES Model Description Of Enctosure 2308 1 Benchtop Enclosure for use with one Model 234 PCB 2308 12 VMEbus rack mount case with built in power supply for use with up to 12 Model 234s 6 2 OPTIONS Model Description Of Option 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 8001 234 Field Installed CalCurve Requires field installation of a new Curve EEPROM Allows instrument to use the calibration data to calculate and output current proportional to temperature Requires calibrated sensor 8002 2
35. hen reversed The new reading is combined with the previous reading to eliminate any thermals present and the sensor resistance and log resistance is calculated With no CalCurve present the output is the log of the resistance Place the T R switch in the R position 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 Q and 20 mA for the log R equal to 6 1 MQ A resistance of 1 KQ results in an output of 12 mA log R equal to 3 If input resistance is greater than 400 kQ output is 0 current A resistance greater than 400 kQ is considered an open and 0 current is used as an alarm indication for a 4 20 mA loop If the I V OUT switch is in the V position 0 20 mA out output is 0 mA for the log R equal to 0 1 Q and 20 mA for the log R equal to 6 1 MQ A resistance of 1 kQ results in an output of 10 mA log R 3 For the Model 234D only although the transmitter output is still log R the display is simply R 2 4 Installation Lake Shore Model 234 234D User s Manual 2 4 1 CalCurve CalCurve formerly called Precision Option is the easiest way to combine the performance of a Lake Shore calibrated sensor with the Model 234 If CalCurve is present Place the T R switch in the T position See Paragraph 3 1 for output current temperature ranges The factory stores the optional Model 8001 234 CalCurve in the unit if it is ordered with the unit The Curve EPROM see Figu
36. ical Model 234 to Sensor Connections Installation 2 3 Lake Shore Model 234 234D User s Manual 2 3 4 Proper Shielding Techniques Since the Model 234 excitation voltage is so low shield resistance sensor leads to avoid inducing measurement errors due to AC noise Use twisted pair cable one pair for current and one for voltage with an overall shield The most common shield configuration connects the shield to the Model 234 SHIELD connection measurement ground potential at one end and leaves the other end open The other end of the shield is left open since most vacuum jackets or feedthrough bulkheads are at earth ground potential Connecting the shield at both ends produces a ground loop that adversely affects measurement Some systems can benefit from continuous shielding such as those in which the shield is carried as a conductor through the bulkhead rather than terminated at it or those in which the vacuum jacket is not at earth ground potential Try different shielding configurations if noisy readings are encountered 2 4 SENSOR MEASUREMENT The Model 234 analog control loop maintains a constant excitation 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 t
37. itcheSs 5 7 5 4 4 Calibration With Serial Interface Commands 5 9 5 4 5 Calibration Verification i 5 11 6 OPTIONS AND ACCESSORIES xrrrrseeeiie iii 6 1 6 0 G n rale aa a cai 6 1 6 1 ENncloSUreS 2 sr 22255 ska ogs lr A un sk sel et alt 6 1 6 2 Options suziaz an iaia iaia 6 1 6 3 Accessoriess i rivale pc E 6 2 6 4 ALEE e E EE edera iaia 6 2 6 5 EIET EEE E E E E EEE 6 3 6 6 Special EQUIPMENt ii 6 3 Figure No Title Page 1 1 Typical Model 234 Front Panel seeen 1 3 1 2 Model 234D Dimensions amp 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 i 2 6 3 1 Model 234 DIP Switch S1 SettingSs ii 3 1 4 1 Serial I O RJ11 Connector Pin Definitions 4 1 4 2 Serial Interface CONNECHIONS serene rr nerne nnen erne 4 2 5 1 Front Panel Connector DetailS i 5 2 5 2 VMEbus Connector DetailS i 5 3 5 3 Model 234 PCB LayOUt i 5 4 LIST OF TABLES Table No Title Page 1 1 Model 234 SpecificatiONS ii 1 5 1 2 Model 2308 12 Case Specifications 1 8 3 1 Conversion Parameters
38. kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk CLS Clear screen PRINT SERIAL COMMUNICATION PROGRAM PRINT TIMEOUT 2000 Read timeout may need more BAUDS 9600 BAUD rate TERMS CHR 13 CHR 10 Terminators are lt CR gt lt LF gt 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 UCASES CMD Change input to upper case IF CMD EXIT THEN CLOSE 1 END Get out on Exit CMD CMD TERMS PRINT 1 CMD Send command to instrument IF INSTR CMD lt gt 0 THEN Test for query RSS If query read response N 0 Clr return string amp count WHILE N lt TIMEOUT AND INSTR RS TERM 0 Wait for response INS INPUTS LOC 1 1 Get one character at a time IF IN THEN N N 1 ELSE N 0 timeout 1 if no chr RS RS INS Add next chr to string WEND Get chrs until terminators IF RS lt gt THEN See if return string is empty RS MID RS 1 INSTR RS TERM 1 Strip off terminators PRINT RESPONSE RS Print response to query ELSE PRINT NO RESPONSE No response to query END IF END IF Get next command GOTO LOOP1 4 4 Remote Operation Lake Shore Model 234 234D User s Manual 4 2 SERIAL INTERFACE COMMAND SUMMARY This Paragraph summarizes Model 234 Serial Interface Commands Command IDN RST C C CAL DAO DA4 DA20 ERASE LOGR OHMS RANGE SCALE SID SID TAG TAG
39. la converts output current to temperature T A BXxI where T temperature in kelvin lour output current in mA and A and B are constants from Table 3 1 depending on temperature out For the 0 20 mA output using a 500 Q resistor for 0 10 V this formula converts output voltage to temperature T C DXxXV out where T temperature in kelvin Vour output voltage and C and D are constants from Table 3 1 depending on temperature Table 3 1 Conversion Parameters for Temperature in K C aoma oov RANGE TEMP K A K B K mA C K D Kv RANGE2 0 20 RANGES RANGE4 RANGES RANGES 75 325 3 2 Operation Lake Shore Model 234 234D User s Manual 3 3 OUTPUT TO LOG R CONVERSION When no CalCurve is present set the T R switch to R The output current or voltage are directly proportional to the log of the resistance reading This is the transmitter output for both the Model 234 and 234D Only the display of the Model 234D is resistance only If the 4 20 mA output is used the current is calculated by log R I 16X 4 where lour is the current measured from the Model 234 Use the following formula to convert the output current to resistance R 103 804 For the 0 20 mA output the current is calculated by log R I 20x out where lour is the current measured from the Model 234 Use the following formula to convert the output current to resistance R 1003 0w
40. ment before performing this procedure fi 2 Disconnect instrument power cord or remove instrument from rack Locate the curve EEPROM U4 Note orientation of existing EEPROM circular dot on the top of the device See Figure 5 4 Use an IC puller or small flat blade screwdriver to remove existing EEPROM from socket Install new curve EEPROM Match the circular dot position of the new device with that of the old one A label indicating the sensor serial number is on top of the curve EEPROM This label should be able to be read with the front panel of the unit to the left Match the orientation of the printing on the Microprocessor U5 adjacent to it Replace instrument power cord or install the instrument in the rack Service 5 3 5 4 Lake Shore Model 234 234D User s Manual Curve EPROM Microprocessor U26 U4 Power Supply Calibration EPROM Output Gain Output old Offset li R38 Figure 5 3 Model 234 PCB Details 111 234 B x W D H qT nm N LSCI C 234 5 3 eps Service Lake Shore Model 234 234D User s Manual 5 4 CALIBRATION The section covers Required Test Equipment in Paragraph 5 4 1 Reference Calibration procedure is provided in Paragraph 5 4 2 Finally the calibration procedure is provided in Paragraph 5 4 3 See Figure 5 3 for the Model 234 PCB layout Allow 5 minutes warm up before performing any calibration procedures The following resistance ranges are
41. ore CGR Series Carbon Glass resistance temperature sensors are the best choice for a highly reproducible sensor from 1 4 K to 325 K and above in magnetic fields up to 19 tesla or higher The Lake Shore GR Series Germanium resistance temperature sensors are recognized secondary standard thermometers used in temperature measurement up to about 100 K for over 30 years Sensitivity for both devices increases rapidly with decreasing temperature both devices are classified according to their 4 2 K resistance value Cernox Carbon Glass and Germanium sensing elements are suspended in a strain free mounting which causes the thermal path through the connecting leads making measurement method and mounting critical to accurate temperature measurements The Model 234 excites the sensor with a constant voltage of 10 mV or less to minimize the effects of sensor self heating at low temperatures Introduction 1 1 Lake Shore Model 234 234D User s Manual The Model 234 employs an analog control circuit to maintain a constant voltage signal across the sensor A series of reference resistors convert the resulting sensor current to a voltage A microcontroller reads the voltage with an A D converter calculates sensor resistance and converts the resistance to temperature by table interpolation requires a CalCurve for temperature conversion The sensor excitation voltage is reversed each reading to compensate for thermal voltages and offsets A c
42. re 5 4 is labeled with the sensor serial number See Chapter 5 for Curve EPROM field installation The optional Model 8001 234 CalCurve data is stored in a temperature versus log of resistance breakpoint table The log of resistance is uniformly spaced over three regions log R of 0 to 2 98 is spaced every 0 02 log R of 3 0 to 3 96 is spaced every 0 04 and log R of 4 0 to 5 6 is spaced every 0 1 Six temperature digits are stored to the 1 mK place A summary of curve breakpoints sensor 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 external power supply connector must be S 760 or S 765 Switchcraft or equivalent plug 0 218 inch O D accepts 0 08 inch diameter pin with 5 VDC on the sleeve and return on the center pin A wall plug in power supply Model 2007 XX 5 VDC Regulated Power Supply can be used with the Model 234 Power Supply input is based on local power requirements as follows MODEL INPUT POWER 2007 12 120 V 60 Hz power source 2007 22 230 V 50 Hz power source CAUTION Never ground both the sensor and the 4 20 mA output Ground either the sensor or the output b
43. rent output at zero until another command or query is sent Set Current Output to 4 mA DA4 Nothing Holds current output at 4 mA until another command or query is sent Set Current Output to 20 mA DA20 Nothing Holds current output at 20 mA until another command or query is sent Erase Curve ERASE Nothing Erases existing sensor curve Do this prior to entering a new curve If a new curve is entered without erasing the existing curve data conflicts could occur Log of Sensor Resistance Query LOGR X XXXXXX Returns value with 1 digit above the decimal point and 6 digits below Returns SHORT if input resistance is less than 1 Q Returns OPEN if input resistance gt 400 kQ Sensor Resistance Query OHMS XXXXXX thru X XXXXX Returns free field 6 digit value with a decimal point The resistance reading is in Q and not log R Returns SHORT if input resistance is less than 1 Q Returns OPEN if input resistance gt 400 kQ Output Temperature Range Query RANGE 1 thru 6 Queries range switch setting Remote Operation 4 7 SCALE Input Returned Remarks SID Input Returned Remarks SID Input Returned Remarks TAG Input Returned Remarks TAG Input Returned Remarks TEMP Input Returned Remarks UNITS Input Returned Remarks Lake Shore Model 234 234D User s Manual Resistance Measurement Scale Query SCALE o thru 9 Queries resistance measur
44. t iii 2 4 2 4 1 Cal urve ci sh oh ee Alenia ala 2 5 2 5 Power CONNECHIONS ii 2 5 3 OPERATION SEEGER iii 3 1 3 0 General ino Ae Delon cd 3 1 3 1 PCB DIP Switch Settings ii 3 1 3 2 Output to Temperature Conversion n 3 2 3 3 Output to Log R Conversion 3 3 4 REMOTE OPERATION rrrrri ein 4 1 4 0 Gener li ifGroncatana di iaia 4 1 4 1 Serial niera ce a ea ea eo e ea rer ain raana aare aiea 4 1 4 1 1 Serial Interface Connections n 4 1 4 1 2 Serial Interface Operation 4 2 4 1 3 QuickBasic Programming Considerations 4 3 4 1 4 QuickBasic Sample Program n 4 4 4 2 Serial Interface Command SUuMMALy 4 5 5 SSERVICE sileielie T 5 0 General ieie ei e ile alia lated 5 1 General Troubleshooting i 5 1 1 No Output On Board LED Off 5 1 2 Output Stops Before Reaching Upper Limit 5 1 5 1 3 Resistance Readings Are INCOrrect 5 1 5 1 4 Open Conditions innisis e 5 1 5 2 Model 234 CONNECHOrS 5 2 5 3 CalCurve Field Installation 5 3 Table of Contents Lake Shore Model 234 234D User s Manual Chapter Paragraph Title Page 5 4 Galibration sartoria ui ila labile 5 5 5 4 1 Required EQUIPment i 5 6 5 4 2 Preparation and General Test n 5 6 5 4 3 Calibration With Range Sw
45. ta both INPUT and LINE INPUT have serious drawbacks for getting input from another device This is because INPUT stops reading data into a variable when it encounters a comma or new line and sometimes a space or double quote and LINE INPUT stops reading data when it encounters a new line This makes INPUT the best function to use for input from a communications device since it reads all characters The program in Paragraph 4 1 4 uses the INPUT function instead of the LINE INPUT statement to retrieve responses from the Controller Remote Operation 4 3 Lake Shore Model 234 234D User s Manual 4 1 4 QuickBasic Sample Program The following program for a PC is an interactive program that prompts the user for a command to send the unit and displays the response A query must be part of the command to get a response from the unit SEREXAM BAS EXAMPLE PROGRAM FOR SERIAL INTERFACE This program works with QuickBasic 4 0 4 5 or QBasic for use on an IBM PC or compatible with a serial interface To use enter an instrument command or query at the prompt The command is sent to the instrument and any query response displays EXIT will exit the program NOTE The INPUT instruction in this example accepts no commas as part of an input string The curve breakpoint command will not operate from this program TIMEOUT may need to be increased for computers running faster than 50 MHz Ikkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk
46. ure 1 4 Model 2308 12 Case Physical Dimensions Introduction Lake Shore Model 234 234D User s Manual CHAPTER 2 INSTALLATION 2 0 GENERAL This chapter covers Inspection and Unpacking in Paragraph 2 1 Repackaging for Shipment in Paragraph 2 2 Sensor Installation Recommendations in Paragraph 2 3 Sensor Measurement in Paragraph 2 4 and Power Connections in Paragraph 2 5 2 1 INSPECTION AND UNPACKING Inspect shipping containers for external damage Make all claims for damage apparent or concealed or partial loss of shipment in writing to Lake Shore within five 5 days from receipt of goods If damage or loss is apparent please notify the shipping agent immediately Open the shipping containers Use the packing list included with the system to verify receipt of the instrument sensor accessories and manual Inspect for damage Inventory all components supplied before discarding any shipping materials If there is freight damage to the instrument file proper claims promptly with the carrier 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 Authorization RGA number from Technical
47. urrent of 4 to 20 milliamps representing either sensor resistance temperature or log transmits The transmitted current changes linearly with resistance temperature or log Output scale depends on the selected temperature range Several switch selected ranges are available Highest accuracy and sensitivity are achieved when the output is set for a narrow temperature 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 Model 234 circuitry The outputs are isolated so several Model 234s can run off the same supply without interference 5 VDC can also be supplied from the pins on the VME bus connector The Model 234 is built on a standard A Size VME Card It fits directly into a single height 3U VME card holder The transmitter does not use the electrical bus format only its physical shape and power supply D 2 234 Temperature Transmitter SERIAL 1 0 LakeShore Figure 1 1 Typical Model 234 Front Panel and Model 234D Rear Panel The Model 234 Temperature Transmitter is available as a stand alone unit or wit
48. use of the product whether based in warranty contract tort or other legal theory and whether or not lake shore has been advised of the possibility of such damages Your use of the Product is entirely at your own risk Some countries states and provinces do not allow the exclusion of liability for incidental or consequential damages so the above limitation may not apply to you 9 Except to the extent allowed by applicable law the terms of this limited warranty statement do not exclude restrict or modify and are in addition to the mandatory statutory rights applicable to the sale of the product to you CERTIFICATION Lake Shore certifies that this product has been inspected and tested in accordance with its published specifications and that this product met its published specifications at the time of shipment The accuracy and calibration of this product at the time of shipment are traceable to the United States National Institute of Standards and Technology NIST formerly known as the National Bureau of Standards NBS or to a recognized natural standard TRADEMARK ACKNOWLEDGEMENT Manufacturers and sellers claim many designations as trademarks to distinguish their products Where those designations appear in this manual and Lake Shore was aware of a trademark claim the designations appear in initial capital letters with a or symbol Apiezon is a trademark of Biddle Instruments CalCurve Carbon Glass Cernox Duo Twist
49. ut not both The Model 2308 10 VMEbus rackmount case has a built in power supply for use with up to twelve Model 234s The built in power supply has a universal input 85 to 265 VAC 47 to 440 Hz 60 watts Installation 2 5 Lake Shore Model 234 234D User s Manual 2 25 in 5 72 cm wide 2 0 in 5 1 cm deep AC DC REGULATED POWER SUPPLY INPUT AC 120V 60Hz 12W OUTPUT DC 5V 600mA CAUTION Indoor Use Only i 6 foot Cord Figure 2 2 Typical Wall Plug In Power Supply 2 6 3 125 in 7 94 cm high C 234 U 2 2 eps Installation Lake Shore Model 234 234D User s Manual CHAPTER 3 OPERATION 3 0 GENERAL This chapter covers Printed Circuit Board PCB DIP Switch Settings in Paragraph 3 1 Output Current and Voltage to Temperature Conversion in Paragraph 3 2 and Output to log R Conversion in Paragraph 3 3 3 1 PCB DIP SWITCH SETTINGS Before placing the unit into service properly configure the Model 234 DIP switch S1 To access the PCB use a flat blade screw 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 the PCB DIP Switch S1 See Fi

234 Manual - Lake Shore Cryotronics, Inc.

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