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Status Registers
Overview
Release 2.1 79
Status Byte The Status byte register contains the STB and RQS(MSS) messages as defined in
488.1. The user can read the status byte register using a 488.1 serial poll or the 488.2
*STB? common command. If the user sends a serial poll, bit 6 will respond with
Request Service (RSQ). The value of the status byte is not altered by a serial poll.
The *STB? query causes the device to send the contents of the Status Byte Register
and the Master Summary Status (MSS) summary message. The *STB? query does
not alter the status byte, MSS, or RQS.
Table 4.11 Status Byte Summary Register
Bit Bit Weight Bit Name Description
01Reserved
12Reserved
2 4 Error/Event
Queue (ERR)
Set if any errors are present in
the Error/Event queue.
3 8 Questionable
Status Register
(QSR)
Set if any bits are set in the
Questionable Status Event
register and the corresponding
bit then the Questionable
Status Enable register is TRUE.
4 16 Message
Available (MAV)
MAV is TRUE if the power
supply is ready to accept a
request from the controller to
output data. FALSE when the
output queue is empty.
5 32 Standard Event
Status Bit
Summary (ESB)
A summary of the Standard
Event Status Register. TRUE
with a bit is set in the Standard
Event Status register.
6 64 Request Service
(RQS)
Master Status
Summary (MSS)
MSS indicates that the device
has at least one reason for
requesting service.
7 128 Operation Status
Register (OSR)
TRUE if a bit is set in the
Operation status register and
the corresponding bit in the
Operation Status Enable
register is set.