GPIB OPERATION
4-56
Status byte when read by serial poll
*SRE
*SRE?
C0074
e
d
d
e
d
d
e
d
d
e
d
d
e
d
d
e
d
d
e
d
d
e
d
d
3
3
3
7
7
7
5
5
5
1
1
1
2
2
2
6
6
6
4
4
4
0
0
0
<erb>
<mss>
<mav> <hsb>
<ssb>
<csb>
-
<esb>
Status Byte Register
Service Request Enable Register#
Register
Read/Write
Commands
➤
➤
➤
Service
Request
Generation
# Bit 6 in this register ignores data sent by *SRE and always returns 0 in response to *SRE?
<erb> is a device defined queue summary bit indicating that the error queue is non-empty.
<rqs> is set by a request for service and is cleared by the poll.
<esb> is the standard event register summary bit.
<mav> is 'message available' indicating that the output queue is non-empty.
<hsb> is 'hardware status' summary bit
<csb> is 'coupling status' summary bit
<ssb> is 'instrument status' summary bit
<rqs>, <esb> and <mav> are defined in IEEE 488.2
<rqs> (request for service) will produce an SRQ at the controller. It is set by a change to either the Status
Byte or the Service Enable Register that results in a New Reason for Service. It is cleared when <mss>
goes FALSE (i.e. no reason for service) or by Serial Poll.