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S:\agilent\8920\8920b\PRGGUIDE\BOOK\CHAPTERS\usehpib.fb
Chapter 1, Using GPIB
Getting Started
• Guideline #6. Numeric values are returned in GPIB Units or Attribute Units only.
When querying measurements or settings through GPIB, the Test Set always returns
numeric values in GPIB Units or Attribute Units, regardless of the current Display
Units setting. GPIB Units, Attribute Units and Display Units determine the units-of-
measure used for a measurement or setting, for example, Hz, Volts, Watts, Amperes,
Ohms. Refer to “Specifying Units-of-Measure for Settings and Measurement
Results” on page 75 for further information.
For example, if the Test Set’s front panel is displaying TX Frequency as 835.02 MHz,
and the field is queried through GPIB, the value returned will be 835020000 since the
GPIB Units for frequency are Hz. Note that changing Display Units will not change
GPIB Units or Attribute Units. Note also that setting the value of a numeric field
through GPIB can be done using a variety of units-of-measure. The GPIB Units or
Attribute Units for a queried value can always be determined using the :UNITs?
command or :AUNits? command respectively (refer to “Number Measurement
Syntax” on page 177 or “Multiple Number Measurement Syntax” on page 179,
for command syntax).
Control Annunciators
The letters and symbols at the top right corner of the display indicate these
conditions:
• R indicates the Test Set is in remote mode. The Test Set can be put into the remote mode
by an external controller or by an IBASIC program running on the built-in IBASIC
controller.
• L indicates that the Test Set has been addressed to Listen.
• T indicates that the Test Set has been addressed to Talk.
• S indicates that the Test Set has sent the Require Service message by setting the Service
Request (SRQ) bus line true. (See “Status Reporting” on page 239.)
• C indicates that the Test Set is currently the Active Controller on the bus.
• * indicates that an IBASIC program is running.
• ? indicates that an IBASIC program is waiting for a user response.
• - indicates that an IBASIC program is paused.