MKS 651D Series, User Manual, Page: 141 / 162

Chapter Seven: Maintenance and Troubleshooting Troubleshooting
129
How To Calibrate the Span of the A/D Converter using Remote RS-232 Operation
To calibrate the span of the A/D converter:
1. Apply a known voltage of b6.6 Volts and +7.4 Volts to the pressure input pins 2
and 12 on the Transducer connector. (connect pin 12 to pin 5)
Refer to Table 9, page 22, for the Transducer connector pinout.
2. Send the command:
Y 1 value
where value : known voltage from step 1, expressed as a percent
(applied voltage / FS)
For example, if the applied voltage is +7.0 Volts, and the full scale range is 10 Volts,
then
value = +70, and the command is:
Y 1 + 70.00
The controller takes the entered value from the command and assigns it to the converter
reading of the pressure as an analog input. In this example, the 7 V input = 70.00.
Calibrating the span of the A/D converter may take up to 5 seconds.
3. Check that the calibration is finished by sending the checksum error request:
R 52
The controller responds to the request immediately after the span calibration is complete.
The controller responds with the message:
CS value
where
value
: 0 = OK
1 = Error Condition
An example response, if the span calibration was successful, is:
CS 0
An example response, if the span calibration was not successful, is:
CS 1
If the response to the R52 checksum request is ‘‘1’’, the controller is reporting that the
checksum error still exists. In that case, repeat the A/D converter calibration.
If the error persists, it indicates a hardware failure of the EEPROM. Contact any MKS
Service Center, listed on the inside back cover of this manual, for assistance.