Manual - 8500A Series Peak Power Meter - Giga-tronics

Remote Operation
3.4.1 Error Conditions
When it is first activated, the PPM will check to see if there has been a change in its internal software.
An SRQ will be sent over the bus if any change is detected. The PPM will attempt to capture the PROM
data from the detector(s), and will also check the detector’s serial number(s) to see if there has been a
detector change. The instrument will also detect a change in detectors that occurs at any time during a
test and measurement operation. When detectors are changed, the instrument will request service and
calibration will be required. No data can be taken over the GPIB until recalibration has been completed,
or the detector has been removed or changed for the detector that was last calibrated.
If the instrument detects a power over range condition, it will send an SRQ. If data is being collected to
be output over the bus, the data will still be available in memory and can be read out. However, if the
power level was outside the PPM’s normal range the data may not be accurate. This data may still give
some idea of what power was being measured. If a serious over-range condition occurred, detector
damage may have resulted.
If an under-range condition occurs when the PPM is operating under bus control and it is not collecting
data to be sent over the bus in the Update Data Trigger Reset, or Update Data Continuously Modes, then
the instrument will not signal the controller (with a service request) that the under range condition has
occurred. Instead, the data display will display the standard under range message of ———. However, if
the instrument is collecting data to send over the bus and the data is under range, then the PPM will
request service (if SRQ is enabled) to report the condition if you asked for it to be reported. If the
instrument is in the Update Data Trigger Reset Mode, the under range condition will be reported (via a
serial poll) before the output ready condition. The data that will be output over the bus, if the data is still
requested, will be an impossible value to indicate to the controller that an under range condition has
occurred and that the data is not valid. If the log (dBm) mode were in use, the instrument would output a
reading of -999.99 dBm. In the linear mode, the reading will be 000.00E-99.
Manual No. 20790, Rev C, November 1998 3-37
Superceded by Revision D, March 2009