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Calibration 77
CALibration:SAVE
Writes the present calibration constants into the EEprom. This command does not have to be sent until all ranges and modes
have been calibrated. If the unit is turned off before CAL:SAVE is sent, the new calibration constants are lost.
Calibration Flowcharts
The flowcharts in Figures 6-2 and 6-3 describe the calibration procedures for "A" and "B" modules, respectively. They
correspond to the example calibration programs. The flowcharts indicate the appropriate statement that is used in the
program example to accomplish each step. They also indicate when to set the power supply to the appropriate voltage and
current output. Refer to the Calibration Information (Table 4) in your module manual for the variable values, power supply
settings, and current shunts.
Calibration mode is turned on at the beginning of the calibration procedure. Remember to save the calibration constants
after you have verified that they are within specifications. Do not turn calibration mode off until after you have saved the
new calibration constants - otherwise the new calibration constants will be lost.
Note When calibrating the high calibration point of the high current range and high current transient level, you
must wait about 30 seconds for the internal current shunt of the module to stabilize with the full current
applied before you execute the CAL:MEAS:HIGH command. Because the high current range
calibration cause the module to heat up, you should also allow about 30 seconds time for the module to
cool down to room temperature before continuing to calibrate any other modes or ranges.
One shortcut that is used in this calibration procedure is that the readback DAC is calibrated for current readback after the
high current range calibration, and calibrated for voltage readback after the voltage range calibration. This is because the
readback setups are the same as the setups for the high current and voltage ranges. Another shortcut is that the same values
are used to calibrate the main DAC as well as the readback DAC. You may wish to use different values to calibrate the
readback DAC to optimize accuracy.
It is not necessary to calibrate the current readback for the low current range or for reading back resistance values. This is
because the high current readback calibration takes care of the low current range. The resistance values that are read back
are calculated based on the voltage at the input terminals and the current through the internal current shunt resistor. If the
readback DAC has been calibrated for voltage and current readback, resistance readback will be accurate.
Note Remember to turn the unit off after you have saved the new calibration constants. When the unit is turned
on again, the new calibration constants are used to recalculate the software OP and OC limits.
Example Programs
Each example program in this chapter is written in the, Agilent BASIC Language. If you are using an HP Series 200/300
computer, simply type in the program and run it. If you are using a different computer or programming language, you will
have to modify the program before you can run it.
The program can be used to calibrate all of the modules. You must specify the Electronic Load address and the channel
number of the module that you are calibrating as shown in lines 10 and 20. (The program assumes address 705, channel 1.)
Then you must make the variable assignments for the module that you are calibrating in lines 40 through 90. Refer
to the Calibration Information table of the module you are calibrating for the values to assign each variable. Do not change
the last value (Flag) in lines 40, 50, 70, 80, and 90.
When the program is run, it will stop at appropriate places and prompt you to set the power supply according to the
calibration table, enter your measured values into the computer, and verify that the values are within specifications.