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CALIBRATION
TEC Calibration Procedures
06_03 TCM-39032 13
CHAPTER 3
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 current 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.
Local 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
local (front panel) operation. The next section will cover remote calibration of the
LM335 sensor.
1 Set the SENSOR SELECT switch (back panel) to the LM335 position (position --03).
Select the TCM-39032 for calibration by pressing the appropriate (ADJUST) LAS / TEC
switch (so that the TEC indicator is orange).
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 sensor calibration mode by pushing the (GPIB) LOCAL and (TEC
DISPLAY) R switches at the same time. The sensor code (SENSOR SELECT switch
position) value will be displayed for 2 seconds. After this, the TEC display will indicate
sensor reference voltage in mV. The LDC-3900 will beep when it is ready to accept a new
calibration value.
4 Press and hold in the (PARAMETER) SET switch and turn the ADJUST knob until the
TEC display indicates the same voltage as shown on the precision voltmeter.
5 Release the (PARAMETER) SET switch to store the new value into non-volatile memory
on the TCM-39032. After the SET switch is released, the LDC-3900 will beep and return
to its former state (before calibration).