Calibration Constants and Non-Volatile Memory

The accuracy of a channel output depends upon a number of calibration constants. Calibration constants are stored in two locations within the module; in non-volatile memory and in RAM. The constants in RAM are used by the module to adjust all outputs.

When the module is used with the SCPI driver, the RAM constants are loaded from the non-volatile memory at power-up. You can adjust the RAM calibration constants without disturbing the non-volatile memory constants (creating a temporary calibration).

Non-volatile memory has a finite number of writes. Writing the calibration constants to non-volatile memory, therefore, reduces the life of this memory. If you are calibrating the module at 90 day or 1 year intervals, write the new constants into non-volatile memory. The new constants will be used following power-up. If you are calibrating the module more frequently (daily, for example), write the new calibration constants into RAM, but do not write to non-volatile memory.

The adjustment procedures shown in this appendix demonstrate both methods of writing calibration constants.

Equipment Required

The following equipment is recommended for calibration and adjustment.

Key specifications are listed to allow for equipment substitutions.

Model

Requirements

 

 

Digital Multimeter (DMM)

Voltage measurements to ±16.8 V

51⁄2 or 61⁄2 digit

Four-wire Resistance measurements

 

from 50 Ω to 500 Ω

 

 

Making Connections

All adjustment can be performed using the CAL output terminals. The CAL output terminals provide one set of connections for both voltage and current adjustment.

Optionally, you can also perform the adjustment at each channel output (to include the output relay contacts in the path). Before beginning adjustment procedures, you must send the DIAGnostic:CALibration:OUTPut CHANnel command to set the adjustment point at the channels instead of the CAL output terminals. Adjustment at each channel output will require individual connections. You must make a four-wire connections for the adjustment procedures.

155 Voltage/Current Output Adjustment

Appendix D