HP 8901B Operation And Calibration Manual page 304

Model 8901B Operation
PROCEDURE
To cause the instrument to run through its internal checks and reset the instrument to its default state,
turn the instrument off, then on again.
To reset the Modulation Analyzer to its default state but bypass the internal power-up checks, select
INSTR PRESET (Blue Key, AUTOMATIC OPERATION), or issue a device clear command from an
HP-IB controller.
To initiate the internal power-up checks, select
40.0
SPCL.
HP-IB PROGRAM CODES
INSTR PRESET (Device Clear)
=
IP
SPCL =
SP
The instrument can also be preset using the device clear bus command. (Refer
to the Remote section
on page
3-24.)
COMMENTS
Setting the Instrument to a Known State
The Instrument Preset feature is a very simple means of setting the instrument to a known state when
writing test procedures involving the Modulation Analyzer.
Losing Instrument States with a New Controller Assembly
After plugging in a new controller Assembly, some or all of the instrument
states
stored through
power-down may be non-existent. If this information is lost
a. The Recall function reverts to the Instrument Preset state.
b. The RF Power measurement will: (1) display Error 15,
(2)
light the UNCAL and RECAL
annunciators, and (3) use the default zero and calibration factors. (The
RF
power calibration
factors must be re-entered.)
c.
AM and FM calibration factors will be 100% when enabled (using Special Function 16 or 17).
Instrument Preset Clears Pending Require Service Messages
When the instrument is preset, any pending Require Service Message is cleared. (For more details,
refer to Receiving the Clear Message, in Remote Operation.)
CLEAR Key
The HP-IB Clear message should not be confused with the front-panel CLEAR key or its CL HP-IB
code. The HP-IB Clear message presets the instrument. The CLEAR key clears the display and returns
the instrument to its previous state.
Alternative to Turning the Instrument Off and then On
Use special function
40.0
to cause the Modulation Analyzer to pass through its internal checks. (Special
function 40.0 is not accessible from the HP-IB.)
Instrument Preset 3-21
1