Appendix C: Status model
Models 707B and 708B Switching Matrix Reference Manual
C-18
707B-901-01 Rev. A / August 2010
SPE, SPD (serial polling)
For the GPIB interface only, the SPE and SPD General Bus Commands are used to serial poll the
Switching Matrix. Serial polling obtains the serial poll byte (status byte). Typically, serial polling is
used by the controller to determine which of several instruments has requested service with the SRQ
line.
Service requests (SRQs) and connections
SRQs affect both the GPIB and the VXI-11 connections. On a GPIB, the SRQ line will be asserted.
On a VXI-11 connection, an SRQ event will be generated.
Status byte and service request commands
The commands to program and read the Status Byte register and Service Request Enable register
are listed in
Status byte and service request commands
(on page C-18). Note that the table includes
both common commands and their script command equivalents. For details on programming and
reading registers, see
Programming enable and transition registers
(on page C-13) and
(on page C-14).
To reset the bits of the Service Request Enable register to 0, use 0 as the parameter value for the
command (for example,
*SRE
0
or
status.request.enable = 0
).
Status Byte and Service Request Enable Register commands
Command Description
*STB?
or
print(status.condition)
Read the Status Byte register.
*SRE <mask>
or
status.request_enable = <mask>
Program the Service Request Enable register where
<mask>
= 0-255.
*SRE?
or
print(status.request_enable)
Read the Service Request Enable register.
