HP 8921A Programmer's Manual page 262

Chapter 5, Advanced Operations
Status Reporting
Table 19 Standard Event Status Register Bit Assignments (Continued)
Bit Binary
Number Weighting
2 4
1 2
0 1
262
Condition
Query 1 = An error has occurred while trying to read the Test Set's Output
Error Queue. The following events cause a query error:
a. An attempt is being made to read data from the Output Queue when
no data is present or pending.
b. Data in the Output Queue has been lost. An example of this would
be Output Queue overflow.
Request 1 = The Test Set is requesting permission to become the Active
Control Controller on the HP-IB bus.
Operation 1 = The Test Set has completed all selected pending operations and is
Complete ready to accept new commands. This bit is only generated in response
to the *OPC IEEE 488.2 Common Command.
The following sections show the syntax and give programming examples (using
the HP BASIC programming language) for the Common Commands used to
access the Standard Event Status Register Group's registers.
Reading the Event Register
Syntax
*ESR?
Comment