Instrument functions that take a specific amount of time to complete will be noted with an asterisk (*) in
the following discussion.
During the time the PPM is processing a function such as calibration, zeroing, or self test, the instrument
will continue to be active on the bus. Any new commands may not be received if previous activity is not
already completed. No output will be given and, if any commands are sent by the controller, only the first
byte will be accepted. The PPM will then send Not Ready for Data until the function is complete.
When the particular function completes, the PPM will request service and send SRQ if SRQ has been
enabled. Successful completion of the task is verified by checking the value of the status byte. A listing
of Status Codes is given in Section 3.6. If SRQ has not been enabled, the controller can only learn the
result of the operation by asking for the status byte with the STAT command.
3.3.1 Common Mode Functions
Calibration Commands
It is advisable to use the PPM’s SRQ capabilities to monitor whether the calibration has completed and is
successful or not. A serial poll can be conducted and the returned Status value interpreted. See
Section 3.4 for SRQ features, and Section 3.6 for applicable Status Code values.
* CALA Calibrate channel A detector
* CALB Calibrate channel B detector
Temperature Difference Since Last Calibration Commands
DTMP Output the Difference in the temperature of each detector since calibration. This
command causes the temperature to be read from each detector (or whatever detector
is connected). It will be formatted as described under Temperature Difference Output
Mode in Section 3.2.5, and is useful for determining whether recalibration of
detectors should take place. Normally the PPM can maintain accuracy within ±5 °C
of the temperature of calibration.
Autozero Detectors Commands
* ZERA Zero channel A detector
* ZERB Zero channel B detector
Store or Recall Setup Commands
STORnn Store current PPM settings in non-volatile setup memory number n.
n = number between 1 and 10.
RECLnn Recall PPM setting from non-volatile memory n, and make it the current setting.
n = number between 0 and 10. Setup number 0 cannot be used for storage. It is the
last setup before power was turned off or the PPM received a Device Clear from the
GPIB controller.
Hide and Unhide Frequency Information Commands
FQHD Hide the frequency information
FQDS Display the frequency information
Remote Operation
Manual No. 20790, Rev C, November 1998
3-15
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