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

Remote Operation
The instrument must always be in an output mode. It sends output information when it receives a
command to initiate another output mode, or when a current output mode is completed and terminates
itself. The self terminating modes are Plot, Output Temperature Difference Since Calibration, Output
Status Byte, and Stand Alone Plot. When these modes complete, the PPM will not send any more data
until it is untalked (the Stand Alone Plot untalks itself). When untalked, the default output mode becomes
either Update Data Trigger Reset or Update Data Continuously, depending on which mode was last
initiated. When power is first applied to the instrument, the default output mode is Update Data Trigger
Reset.
Before selecting any of the PPM Output Modes described above, required parameters should be set so
that the PPM data that is taken will be valid. For example, plotting commands will not work unless the
PPM has been set to the Graph Mode.
Update Trigger Reset Output Mode
A string of four characters (UPDT) must be sent over the bus to the PPM to access this mode of
operation. If you are using BASIC on an HP Series 200 computer, the command might look like:
where:
OUTPUT 704; UPDT
OUTPUT is the GPIB command to send the letters following the semicolon.
The 7 in 704 is the HP instruction that the output is to go via the GPIB interface.
The 04 in 704 is the Listen/Talk address of the PPM. The Listen/Talk address must be set with
the MENU key on the PPM’s front panel (see the Menu (6) description in Appendix B).
In the Update Trigger Reset Mode, the PPM will not send any data until it receives a trigger reset. When
the trigger reset is received through the GPIB, the instrument is set to record the next measurement. If the
instrument is in the Peak or Graph Mode, the measurement (power reading at the cursor location) will be
taken the next time the instrument is triggered. Triggering can be either internal or external, depending on
how the instrument has been configured. The recorded measurement data will be output through the GPIB
when the PPM next enters TACS (Talker Active State).
The trigger reset can take one of the following two forms:
A. The universal GPIB command, GET (Group Execute Trigger), can be sent over the bus when the
PPM is listen-addressed, or
B. The controller can send the UPDN (Up-date Data Now) command to transfer the last data taken to
the GPIB buffer (e.g. OUTPUT 704; UPDN).
When the PPM completes the measurement and has the data ready to output, it will request service if it is
not in TACS and has SRQ enabled. Entering TACS will clear the service request if the instrument has not
already been serviced directly by the GPIB controller program.
Manual No. 20790, Rev C, November 1998 3-5
Superceded by Revision D, March 2009