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CALIBRATION
TEC Calibration Procedures
14 TCM-39032
CHAPTER 3
Remote Operation LM335 Sensor
The following procedure is for calibrating the LM335 sensor so that the
temperature measurement will be as accurate as possible. This procedure is for
remote operation.
1 Set the SENSOR SELECT switch (back panel) to the LM335 position (position --03).
2 Connect a precision 6.8 KΩ (metal film) resistor and a precision voltmeter in parallel at the
sensor input of the TCM-39032 (pins 7 and 8).
3 Enter the “TEC:CHAN x” command over the GPIB to select the channel of the TCM-
39032 to be calibrated, where x = the channel number.
Enter the “TEC:CAL:SENsor” command over the GPIB. The TEC display will show the
current value in µA. The LDC-3900 will beep when it is ready to accept a new calibration
value.
4 Input the actual voltage (in mV) measured by the external voltmeter (as an <nrf value>)
via the “TEC:R <nrf value>” command.
If this value is to be measured and entered remotely via a GPIB controlled DMM, for
example, the measured value of the current should not be entered until the LDC-3900 is
ready to receive it.
The LDC-3900 will be ready to receive the voltage value when, after a
“TEC:CAL:SENsor?” query is sent, the response from the LDC-3900 is “1”.
After the “TEC:R” value is entered, the “*OPC?” query may be used to determine when
the calibration sequence is done. However, the “*OPC”, or “*WAI” command, or “*OPC?”
query should not be issued until after the expected “TEC:R” value is entered, or the
system will “hand”. This happens because the LDC-3900 will wait indefinitely for an input,
yet not allow any input until the calibration is finished.
5 Once the “TEC:R” value is sent, the LDC-3900 will beep and return to its former state
(before calibration). The “OPC?” query may be used (after the “TEC:R” value is sent) to
determine when the calibration is completed.
The operation complete flag (bit 0 of the Standard Event Status Register) may be used to
trigger a service request. This type of interrupt is enabled by setting bit 0 of the Service
Request Enable Register (via the *ESE command) and bit 5 of the Service Request
Enable Register (via the *SRE command). Service request (SRQ) handling depends on
the GPIB hardware. Refer to the GPIB manual for details.