ETS-Lindgren 2090 Controller - Manual (Page 85)

Model 2090 Multi-Device Controller
Status (MSS) remaining bits of the Status Byte
Register and the Status Byte Enable
Register is non-zero. This value is
returned in response to a *STB? query.
-or-
Request Service
(RQS)
Set when a Service Request has been
generated (when the controller's GPIB
SRQ line is asserted). This value is
returned in response to a Serial Poll.
Undefined 7 -
of a
ondition which needs attention by issuing a Service
herwise it will be FALSE.
A GPIB device informs the controlling program
c
Request. It does so by asserting the SRQ line of the IEEE
488 bus. The controlling program can then detect that the
SRQ line has been asserted and perform a Serial Poll to
determine which device or devices are requesting service.
If a device is requesting service, bit six of the Serial Poll
Response Byte will be TRUE, ot
The remaining bits of the Response Byte are the bits of the
Status Byte Register. Upon performing a Serial Poll, the
SRQ line will be unasserted to allow other devices to
request service. The RQS (Request Service) flag is TRUE
as long as the SRQ line is asserted.
A Service Request is generated any time one of the bits in
the Status Byte Register makes a transition from FALSE to
TRUE while the corresponding bit in the Service Request
Enable Register is TRUE. A Service Request will also be
generated if a bit in the Status Byte Register is TRUE and
the corresponding bit in the Service Request Enable
Register makes a transition from FALSE to TRUE due to
the use of the *SRE GPIB command.
©ETS-Lindgren, April 2006 85
Revision G– P#399199