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971B UniMag™ 

21 

Operation manual 

 

 

Calibration and Adjustment 

The 971B is factory calibrated when delivered and in many applications further calibration is not required. If 

the sensor element has been contaminated or damaged by process gases, adjustment of zero and full 

scale can be executed to compensate for small measurement errors. 

 

Pressure unit setting

 

The transducer can provide digital and analog output in torr, mbar and Pascal pressure units. 

When changing pressure unit all parameters such as setpoint settings are automatically converted to the 

new unit, so it will represent the same pressure level. All pressure parameters such as setpoint settings and 

calibration values must be entered in the actual transducer unit setting. 

Change of pressure unit calibration setup: 

Command: 

@253U!PASCAL;FF 

Command values: 

TORR, MBAR, PASCAL 

 

Command reply: 

@253ACKPASCAL;FF 

Query: 

@253U?;FF 

Query reply: 

@253ACKTORR;FF 

Factory default: 

TORR 

 

The torr unit is most common in the US and mbar is most common in Europe. Pascal is the official pressure 

unit as specified by SI (from the French 

Le 

S

ystème 

I

nternational d'Unités

) and is widely used in Asia. 

 

Cold cathode zero adjustment

 

The Cold Cathode zero adjustment allows the user to adjust the cold cathode zero reading. 

 

Executing zero adjustment

 

To obtain measuring performance the transducer should be evacuated to pressure below 5×10

-8 

Torr. 

 

If the Cold Cathode zero adjustment is executed at high pressure, the measurement below the 

zero value can become unreliable. Always zero at the system base pressure. 

 

 

Command: 

@253VAC3!2.00E-8;FF 

Command values: 

1.00E-6 to 1.00E-8 Torr 

 

Command reply: 

@253ACK;FF Query:

 

@253VAC3?;FF 

Query reply: 

@253ACK0.00+00;FF 

Reset to default: 

@253FD!VAC3;FF 

Factory default: 

Factory adjustment value

 

Value out off range:  @253NAK172;FF 

 

Cold cathode full scale adjustment

 

The Cold Cathode full scale adjustment allows the user to adjust the cold cathode reading at high pressure. 

 

Command: 

@253CFS!4.00E-3;FF 

Command values: 

1.00E-4 to 5.00E-3 Torr 

 

Command reply: 

@253ACK;FF 

Query: 

@253CFS?;FF 

Query reply: 

@253ACK0.00E+0;FF 

Reset to default: 

@253FD!CFS;FF 

Factory default: 

Factory adjustment value

 

Value out off range:  @253NAK172;FF 

Summary of Contents for UniMag 971B

Page 1: ...ag 1 Operation manual 971B UniMag Vacuum Pressure Transducer RS232 RS485 Display Operation and Installation Manual P N 100017129 971B UniMag Transducer Operation and Installation Manual Revision J February 2020 ...

Page 2: ...mal operation e If the product has been dropped or the enclosure has been damaged f When the product exhibits a distinct change in performance This indicates a need for service Service and Warranty Some minor problems are readily corrected on site If the product requires service contact the MKS Technical Support Department at 1 833 986 1686 If the product must be returned to the factory for servic...

Page 3: ... respective owners No part of this work may be reproduced by any method including photocopying and recording or by any information or retrieval system without written permission of MKS Instruments Inc Table of Contents Proprietary Information 3 Copyright Information 3 Table of Contents 3 Safety Information 4 Symbols used 4 Safety Precautions 4 Unpacking 5 Description 6 971B Functions 7 LED Status ...

Page 4: ...ections Wrong electrical connections can cause permanent damage to the transducer or interference to measuring performance Refer to Electrical connections description page 7 Fuse The 971B power supply input has an internal thermal fuse The fuse is self recoverable and should not be changed Explosive Environments Do not use the 971B in presence of flammable gases or other explosive environments Cor...

Page 5: ...tor and sensor sealing type Transducers can be delivered with customer configuration of various parameters like setpoint settings and these specials have additional 4 digits after the regular part number Flange Interface Analog out Connector Relays Enclosure sealing 971B 1 1 0 2 0 0 Standard viton sealing 2 SUBD 15pinHD male no relay 3 SUBD 15pinHD male 3 relays 5 SUBD 15pinHD male 3 relays Dual A...

Page 6: ...re accelerated towards the anode and will ionize molecules by collision The magnetic field deflects the electrons causing them to spiral as they move across the magnetic field to the anode This spiraling movement increases the opportunity for them to encounter and ionize the molecules The ionization of the molecules creates an electric current as a function of the pressure Applications The 971B ca...

Page 7: ...ucer is delivered with customer specified parameters the User Switch is disabled For enabling the switch see page 22 LED Status Indicator The red green LED status indicator has the following stages 1 GREEN Normal operation 2 2 sec RED Power on sequence 3 GREEN 1 sec flash cycle Test mode TST ON see page 23 4 GREEN 0 5 sec flash cycle Cold Cathode high voltage turned on 5 Red 0 5 sec flash cycle Co...

Page 8: ...rmance avoid large temperature gradients and direct cooling like air condition air stream or direct heating like a pump exhaust stream Bake out The transducer electronics can withstand 80 oC 176 oF when the power is turned off Contamination Locate and orient the 971B where contamination is least likely If the transducer is backfilled with a liquid like pump oil the sensor can be cleaned Refer to S...

Page 9: ...nect the positive analog out and negative analog out pins to a differential input voltmeter or an analog to digital A D converter Do not connect the negative side of the analog output to the negative side of the power supply input or to any other ground Doing so will cause half of the power current to flow through this wire Measurement errors in the output voltage may be seen due to the voltage dr...

Page 10: ...t Connected PIN Description 1 RS232 Transmit 2 RS232 Ground 3 RS232 Receive 4 RS232 Receive 5 RS232 Ground 6 RS232 Transmit Input Output Wiring 971B I O Connector 15 pin 15 pin male HD DSUB 1 Relays are optional See part number page 3 Cold cathode external control pin 13 must be floating or shorten to power supply ground pin 4 Do not connect to a voltage source Connection to voltage source can cau...

Page 11: ...nment cable quality and communication speed but relative long cable spans up to 1 200m 4 000 ft is possible There are 2 wires other than ground that are used to transmit the digital RS485 signal The 971B uses half duplex communication Always use high quality shielded data cables for serial communication For long cable runs use twisted pairs See also Accessory and Replacement part number page 36 Th...

Page 12: ...also offers communication software examples that can be downloaded at www mksinst com vtsw In OEM applications transducer communication software routines are normally integrated with other system control software Query and Command Syntax Queries return current parameter settings commands change the parameter setting according to the value the user enters into the command syntax Each query or comma...

Page 13: ...and all transducers will transmit a reply Commands sent with address 255 will be executed by all transducers on the network but the transducers will not transmit replies For example use address 254 to communicate with a device if its address is unknown Change of Address Command 253AD 123 FF Command values 001 to 253 Command reply 253ACK123 FF Query 254AD FF Query reply 253ACK253 FF Factory default...

Page 14: ... de energizing spike protection Inadequate protection can cause permanent damage to the transducer or interfere with the analog output signal Always ensure that inductive inrush currents do not exceed relay contact rating An arc suppression network as shown schematically to the right is recommended The values of the capacitance C and the resistance R can be calculated by the following equations C ...

Page 15: ...ly 253ACKON FF Setpoint setup by PDR900 Controller 1 Edit Setpoint Setpoint 1 Setpoint Value 1 Enter set point value 5 00E 6 Torr 2 Edit Setpoint Setpoint 1 Direction 1 Select set point direction 3 Edit Setpoint Setpoint 1 Hysteresis 1 Enter set point hysteresis value Only if other than default 10 of set point value is required 4 Edit Setpoint Setpoint 1 Enable 1 Enable set point Enter pressure 5 ...

Page 16: ...tpoint safety delay Command 253SPD ON FF Command values ON OFF Command reply 253ACKON FF Query 253SPD FF Query reply 253ACKON FF Factory default ON Integrated Touch Display For 971B transducer versions with integrated touch display it is possible to see information about setpoints sensors model and measurements unit A pressure threshold alarm can be set and for transmitters with multiple sensors i...

Page 17: ... the screen to toggle through the different info screens and eventually go back to Settings Model info 1 4 Model info 2 4 Model info 3 4 Model info 3 4 Transducer P N Gas type Interface type User switch ON OFF Serial number Transducer firmware version Connector type Setpoint delay 50ms ON OFF User tag Display firmware version Number of available relays Relay communication delay ON OFF Communicatio...

Page 18: ...When enabling level trig the cold cathode sensor will be on when pin 13 is shorten to ground pin 4 and turned off when pin 13 is floating Enabling level trig Command 253SW OFF FF Command reply 253ACKOFF FF Analog Pulse trig When enabling pulse trig the cold cathode sensor will be turn on when cold cathode enable pin 13 is shorten momentarily to ground pin 4 and turned off when cold cathode enable ...

Page 19: ...f the measuring range 1 00E 7 to 1 00E 8 Torr 2 digits resolution 1 50E 8 5 00E 3 to 1 00E 7 Torr 3 digits resolution 1 230E 4 Measuring noise External sources can interfere with the sensor signal and cause noise in the signal The low measuring range is most sensitive to measuring noise due to low signal levels Magnetic interference External magnetic sources can interfere with the Cold Cathode sen...

Page 20: ...be used to determine the time interval between Cold Cathode maintenance and service Pressure dose request Query 253TIM3 FF Query reply 253ACK1 23E 2 FF Reset of pressure dose Command 253TIM3 FF Command values The pressure dose reading can be user reset after the transducer has been cleaned or the anode assembly has been replaced The pressure dose reading is only a rough indication of the cold cath...

Page 21: ...common in Europe Pascal is the official pressure unit as specified by SI from the French Le Système International d Unités and is widely used in Asia Cold cathode zero adjustment The Cold Cathode zero adjustment allows the user to adjust the cold cathode zero reading Executing zero adjustment To obtain measuring performance the transducer should be evacuated to pressure below 5 10 8 Torr If the Co...

Page 22: ...ELOW Set point 3 enable EN1 OFF Setpoint safety delay SPD ON Cold Cathode protect setpoint PRO OFF Switch enable SW OFF Analog out 1 AO1 30 1 1 If the transducer is delivered with other analog output than standard mks part number specified then the factory default value will be specified by the specials part number Calibration setup Description Command Parameter FD FD ALL Gas calibration GT NITROG...

Page 23: ...ansducer is delivered with special configuration the lock function will only be temporally disabled and will be enabled again after cycling power cycle or executing the enable lock command The 971B transducer can be delivered with factory locked tamperproof settings for safety interlock applications This option is defined in the special settings If delivered with factory lock the transducer settin...

Page 24: ...art number Query 253PN FF Query reply 253ACK971B 11030 FF Serial Number SN Specifies transducer serial number Query 253SN FF Query reply 253ACK0825123456 FF Time ON TIM The TIM command returns the number of hours the transducer has been on Query 253TIM FF Query reply 253ACK123 FF Cold Cathode Time ON TIM2 The TIM2 command returns the number of hours the cold cathode high voltage has been on Query ...

Page 25: ...5 VDC decade If the transducer pressure unit is changed from Torr to Pascal or mbar the analog output scaling will change as well so it represents 0 5 VDC decade Torr or 0 5 VDC decade mbar or Pascal Torr mbar Vout Torr mbar Vout 1 0E 8 1 5000 1 0E 5 3 0000 2 0E 8 1 6505 2 0E 5 3 1505 4 0E 8 1 8010 4 0E 5 3 3010 6 0E 8 1 8891 6 0E 5 3 3891 8 0E 8 1 9515 8 0E 5 3 4515 1 0E 7 2 0000 1 0E 4 3 5000 2 ...

Page 26: ...tup Command 253AO1 15 FF Command values 10 to 319 xy First digit x 1 PR1 Cold cathode pressure value assignment Second digit y 0 MKS Standard 0 5 VDC decade 1 Edwards APG L 1 99 10 VDC 2 Edwards APG100 3 Edwards WRG 4 Inficon PSG500 Oerlikon Leybold TTR91 5 Inficon MPG400 Pfeiffer PKR251 6 Inficon BPG400 MKS 999 Quattro 7 MKS GP275 8 MKS Moducell 325 9 MKS Moducell 325 x3 10 MKS Baratron 0 1 Torr ...

Page 27: ...3 16E 2 3 16 7 00 7 50E 1 1 00 100 8 00 2 37 31 6 3 160 9 00 750 0 1 000 100 000 10 00 Analog output calibration 5 Inficon MPG400 Pfeiffer PKR251 emulation PTorr 10 Vout 6 875 0 6 Vout log10 PTorr 0 6 6 875 Pmbar 10 Vout 6 8 0 6 Vout log10 Pmbar 0 6 6 8 PPascal 10 Vout 5 6 0 6 Vout log10 PPascal 0 6 5 6 Torr mbar Pascal Vout 1 00E 8 1 33E 8 1 33E 6 2 075 1 00E 7 1 33E 7 1 33E 5 2 675 1 00E 6 1 33E...

Page 28: ...rds AIM S SL emulation provides a strongly non linear output Torr mbar Pascal Vout 1 00E 8 1 33E 8 1 33E 6 2 5 1 80E 8 2 40E 8 2 40E 6 2 5 4 40E 8 5 87E 8 5 87E 6 3 6 10E 8 8 13E 8 8 13E 6 3 2 8 30E 8 1 11E 7 1 11E 5 3 4 1 10E 7 1 47E 7 1 47E 5 3 6 2 20E 7 2 93E 7 2 93E 5 4 5 50E 7 7 33E 7 7 33E 5 4 6 7 40E 7 9 87E 7 9 87E 5 4 8 9 80E 7 1 31E 6 1 31E 4 5 1 30E 6 1 73E 6 1 73E 4 5 2 2 10E 6 2 80E 6...

Page 29: ... 67E 4 6 67E 2 8 656 1 00E 3 1 33E 3 1 33E 1 9 000 5 00E 3 6 67E 3 6 67E 1 9 799 Analog out calibration 18 Pfeiffer IKR251 The Pfeiffer IKR251 emulation provides a log linear output Torr mbar Pascal Vout 5 00E 9 6 67E 9 6 67E 7 2 3240 1 00E 8 1 33E 8 1 33E 6 2 6250 5 00E 8 6 67E 8 6 67E 6 3 3240 1 00E 7 1 33E 7 1 33E 5 3 6250 5 00E 7 6 67E 7 6 67E 5 4 3240 1 00E 6 1 33E 6 1 33E 4 4 6250 5 00E 6 6 ...

Page 30: ...3 hystereses switch value xxxEN1 FF xxxEN2 FF xxxEN3 FF xxxACKOFF FF Set point 1 3 enable status OFF CC Cold Cathode xxxSD1 FF xxxSD2 FF xxxSD3 FF xxxACKBELOW FF Set point relay direction ABOVE or BELOW If set to above relay will be energized above setpoint value If set to below relay will be energized below setpoint value Transducer information Command Response Explanation xxxMD FF xxxACK971B FF ...

Page 31: ...xBR 19200 FF xxxACK19200 FF Set communication Baud rate 4800 9600 19200 38400 57600 115200 230400 xxxAD 123 FF xxxACK123 FF Set transducer communication address 001 to 253 xxxRSD OFF FF xxxACKOFF FF Turn on or off communication delay between receive and transmit sequence Calibration and adjustment Command Response Explanation xxxU MBAR FF xxxACKMBAR FF Set pressure unit setup Torr mbar Pascal xxxV...

Page 32: ...transducer withstand A Cold Cathode sensor element is very mechanical robust to pressure changes and there are no limits on the number of pressure cycles In applications where fast pressure cycles occur the Cold Cathode sensor can be sputtered and this can lead to change of accuracy Q The Cold Cathode sensor chamber has changed color Why A If the Cold Cathode is operated at high pressure 1 00E 4 T...

Page 33: ... compatible with 304 stainless steel 403 stainless steel titanium Ceramic Al2O3 Viton and epoxy resin Q Can the sensor element be changed if contaminated A Yes the cold cathode anode module can be changed or cleaned Refer to Service and Repair page 31 Q How offend does the Cold Cathode sensor require cleaning A Contaminants such as oil vapors from oil lubricated for pump will cause carbonaceous de...

Page 34: ...stment has been executed Incorrect pressure value at high pressure Contaminated sensor Transducer repair required Other gas or gas trace present than transducer gas setting Cold Cathode does not provide measurements If the Cold cathode is turned on a low pressure 1 00E 7 Torr or is contaminated a delay can occur from turning on high voltage to the ionization begins Cold Cathode value is lower than...

Page 35: ...nical polishing P DE FE 1 P N 970B CELLKIT Do not touch cell kit anode module screen screws or clip ring by hand If items are accidental touched by hand use alcohol to clean items Changing the Cell kit 1 Turn power off and remove cable 2 Dismount the transducer from the vacuum system 3 Remove the clip ring 1 using a clip ring remove insert tool p n 100017193 4 Remove the screen 2 5 Unscrew the Tor...

Page 36: ... contact endurance 30VDC 1A load 100 000 min Setpoint relay contact endurance 30VDC 0 2A load 2 000 000 min Setpoint relay response time 100 ms Materials exposed to vacuum 304 and 403 stainless steel Viton Cu Ni and Ag Cu alloy ceramic titanium Internal volume KF25 flange 3 6 cm3 CF2 75 flange 1 9 cm3 KF40 flange 3 1 cm3 Housing material Stainless steel 304 Flange material Stainless steel 304 Weig...

Page 37: ...971B UniMag 37 Operation manual Dimensions KF25 flange P N 971B 2xxx mm Inch Dimensions CF2 75 flange P N 971B 7xxx mm Inch ...

Page 38: ...971B UniMag 38 Operation manual Dimensions KF40 flange P N 971B 9xxx mm Inch ...

Page 39: ...mber Description Interface 100013671 3 m 10ft RS485 100013672 5 m 16ft RS485 100013673 7 6m 25ft RS485 100013674 10 m 33ft RS485 PDR900 Connectors cables Part number Description 100010757 Setpoint Relay 3 pin connector 100013638 Analog output 8 pin connector 100013686 Analog output cable 3 meter 10ft 100013693 RS232 RS485 user communication cable 3 meter 10ft 971B Transducer calibration certificat...

Page 40: ...s The easy way for setup and configuration Data logger tool for data analysing 900 Series VacuumLog software Data logger software Pressure curve plotting Rate of raise diagnostic tool Pump down monitoring Export of data to Excel spread sheet Windows 7 compatible Free version available on http www mksinst com vtsw ...

Page 41: ...ay load 12 Input Output Wiring 8 Internal volume 33 LED Status Indicator 5 Lock function 20 Magnetic interference 2 Manufacturer 21 Model 21 NAK Code 10 NAK180 13 20 31 Operating temperature 33 Part number 3 Part Number 21 PDR900 36 PDR900 controller relays 12 Pressure output 15 16 Process compatibility 6 Query Command list 27 RS232 user interface 9 RS485 user interface 9 Safety information 2 Sens...

Page 42: ...971B UniMag Vacuum Pressure Transducer RS232 RS485 Display Operation and Installation Manual P N 100017129 971B UniMag Transducer Operation and Installation Manual Revision J February 2020 ...

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