CALIBRATION AND TROUBLESHOOTING
Calibration Overview
122 LDC-3700 Series
CHAPTER 5
Remote Calibration of the LDC-3700B Controller
The LDC−3700B Series Controllers can be calibrated remotely via the GPIB Interface. The following
procedures are general guidelines for writing a program to calibrate your instrument.
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 your GPIB hardware. Refer to your GPIB
user’s manual for details.
After a calibration 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 calibration value is entered, or the system will "hang". This
happens because the LDC−3700B Series Laser Diode Controller will wait indefinitely for an input, yet
not allow any input until the calibration is finished.
Thermistor Calibration
The following procedure is for calibrating the 100 µA and 10 µA thermistor current sources so that
the thermistor resistance measurement for these ranges will meet the stated accuracy
specifications.
1 Set the SENSOR SELECT switch (back panel) to the 100 µA position, the TEC display
code is −−01.
2 Using the multimeter, measure and record the exact resistance of your metal film
resistors. (A 4−point probe resistance measurement is recommended.)
3 Connect the correct metal film resistor (See Table 5.1 on page 114) to the sensor input of
the Temperature Controller 15 pin connector on the rear panel Sensor + and Sensor −
terminals.
4 Enter the "TEC:CAL:SENsor" command over the GPIB. The TEC display will show the
resistance value, and will then expect the actual value to be entered, in KΩ.
If this calibration value is to be measured and entered remotely via a GPIB controlled
DMM, for example, the actual value of the resistance should not be entered until the
Controller is ready to receive it. The Controller will be ready to receive the actual
(measured) resistance value when, after a "TEC:CAL:SEN?" query is sent, the response
from the Controller is "1".
5 Once the "TEC:R" value is sent, the Controller will 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.
6 Switch the SENSOR SELECT switch (back panel) to the 10 mA, position, TEC display
code is −−02, and repeat this procedure with the 100 kΩ resistor as the load at the Sensor
+ and Sensor − terminals.
AD590 Sensor Calibration
The following procedure is for calibrating the AD590 sensor so that the temperature measurement
will be as accurate as possible.
1 Set the SENSOR SELECT switch (back panel) to the AD590 position, TEC display code
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