Remote Erasure; Example Calibration Program - Fluke 8842A Instruction Manual

8842A
Instruction Manual
The C0 command can take up to 22 seconds. If during this time the controller continues
to send the 8842A more commands, the commands may fill up the 8842A's input buffer.
If this happens, errors will probably occur.
You can avoid this problem by knowing when these commands are completed. There are
three ways to determine this:
1. Monitoring the Cal Step Complete bit in the serial poll status register. This status bit
2. Setting the SRQ mask to generate an SRQ on Cal Step Complete. An SRQ is
3. Executing a delay in controller software after sending each command. (Not
Although not usually necessary, these methods can be used for other commands as well.

6-25. REMOTE ERASURE

The C3 command allows you to erase the entire calibration memory. The erasure is
executed by sending the string "C3 C0" (equivalent to pressing ERASE and then
STORE). Any command other than C0 after C3 will abort the erasure. To facilitate
remote calibration, the C0 command does not timeout as does the front panel ERASE
button. The selective erasure that is possible from the front panel is intended as a
troubleshooting aid, and is not available over the IEEE-488 Interface.
Note that the erase command can take up to 3 seconds to execute. To prevent timeout
problems with the controller, you must determine when the command is completed
before continuing. Several methods are presented in Timing Considerations, above.
When erasing calibration memory, it is good practice to send the
commands C3 and C0 in the same command string. Sending C3 by itself
could lead to accidentally erasing calibration memory, since the C3
command does not time out as does the ERASE button.

6-26. EXAMPLE CALIBRATION PROGRAM

An example A/D calibration program is shown in Figure 6-5. The program is written in
Fluke BASIC for the Fluke 1722A Instrument Controller. It uses the Fluke 5440A Direct
Voltage Calibrator to perform and then verify the A/D Calibration procedure. In this
program, the 8842A is at bus address 1, and the 5440A is at bus address 7.
6-24
is set false every time the remote processor sends a command to the in guard
processor. It is then set true when the in guard processor completes the command and
is ready to accept more. So you can send a command and loop on a check of the
status, until the command is complete.
generated and the Cal Step Complete bit in the serial poll status response is set when
a cal command is complete. This approach depends on capabilities of the controller
being used.
recommended.)
NOTE