User Manual

15-8 Status Structure 2400 Series SourceMeter
®
User’s Manual
Status byte register
The summary messages from the status registers and queues are used to set or
clear the appropriate bits (B0, B2, B3, B4, B5, and B7) of the Status Byte Regis-
ter. These summary bits do not latch, and their states (0 or 1) are solely depen-
dent on the summary messages (0 or 1). For example, if the Standard Event
Register is read, its register will clear. As a result, its summary message will reset
to 0, which in turn will reset the ESB bit in the Status Byte Register.
The bits of the Status Byte Register are described as follows:
Bit B0, Measurement Summary Bit (MSB) — Set summary bit indicates that
an enabled measurement event has occurred.
Bit B1 — Not used.
Bit B2, Error Available (EAV) — Set summary bit indicates that an error or
status message is present in the Error Queue.
Bit B3, Questionable Summary Bit (QSB) — Set summary bit indicates that
an enabled questionable event has occurred.
Bit B4, Message Available (MAV) — Set summary bit indicates that a
response message is present in the Output Queue.
Bit B5, Event Summary Bit (ESB) — Set summary bit indicates that an
enabled standard event has occurred.
Bit B6, Request Service (RQS)/Master Summary Status (MSS) — Set bit
indicates that an enabled summary bit of the Status Byte Register is set.
Bit B7, Operation Summary (OSB) — Set summary bit indicates that an
enabled operation event has occurred.
Depending on how it is used, Bit B6 of the Status Byte Register is either the
Request for Service (RQS) bit or the Master Summary Status (MSS) bit:
When using the serial poll sequence of the SourceMeter to obtain the sta-
tus byte (a.k.a. serial poll byte), B6 is the RQS bit. See “Serial polling and
SRQ” for details on using the serial poll sequence.
When using the *STB? command (Table 15-3) to read the status byte, B6 is
the MSS bit.