Serial Poll Status Byte - Fluke 5700A Series II Operator's Manual

5-24. Serial Poll Status Byte

The most important and frequently used register is the serial poll status byte, which is the
calibrator's response to a serial poll. This byte is cleared (set to 0) when the power is
turned on. You cannot do a serial poll if you are using the RS-232C port as the remote
control interface. Instead, you can send the *STB? command to get the same information.
Its bits are defined as follows (bits 7, 1, and 0 are always 0):
7 6
0 RQS
MSS
RQS Requesting Service. The RQS bit is set to 1 whenever bits ESB , MAV, EAV, or
ISCB change from 0 to 1 and are enabled (bit 1) in the SRE. When RQS is 1, the
calibrator asserts the SRQ control line on the IEEE-488 interface. You can do a
serial poll to read this bit to see if the calibrator is the source of an SRQ.
MSS Master Summary Status. Set to 1 whenever bits ESB, MAV, EAV, or ISCB are 1
and enabled (bit 1) in the SRE. This bit can be read using the *STB? command
in serial remote control in place of doing a serial poll.
ESB Set to 1 when one or more enabled ESR bits are 1.
MAV Message Available. The MAV bit is set to 1 whenever data is available in the
calibrator's IEEE-488 interface output buffer.
EAV Error (fault) available. A fault has occurred and a fault code is available through
the FAULT? query.
ISCB One or more enabled ISCR bits are 1.
5 4
ESB MAV
Checking the Calibrator's Status
3 2
EAV ISCB
Remote Operation
1 0
0 0
5
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