Stanford Research Systems SIM918, Operating And Service Manual

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3.5 Status Model 3 – 25
At power-on, all status registers are cleared.
3.5.1 Status Byte (SB)
The Status Byte is the top-level summary of the SIM918 status model.
When masked by the Service Request Enable register, a bit set in the
Status Byte causes the
¬ STATUS signal to be asserted on the rear-
panel SIM interface connector.
Weight Bit Flag
1 0 OLSB
2 1 RCSB
4 2 undef (0)
8 3 undef (0)
16 4 IDLE
32 5 ESB
64 6 MSS
128 7 CESB
OLSB : Overload Summary Bit. Indicates whether one or more of the
enabled flags in the Overload Status Register has become true.
RCSB : Reference Clock Summary Bit. Indicates whether one or more
of the enabled flags in the Reference Clock Status Register has
become true.
IDLE : Indicates that the input bu
ff
er is empty and the command
parser is idle. Can be used to help synchronize SIM918 query
responses.
ESB : Event Status Bit. Indicates whether one or more of the enabled
events in the Standard Event Status Register is true.
MSS : Master Summary Status. Indicates whether one or more of the
enabled status messages in the Status Byte register is true.
CESB : Communication Error Summary Bit. Indicates whether one or
more of the enabled flags in the Communication Error Status
Register has become true.
3.5.2 Service Request Enable (SRE)
Each bit in the SRE corresponds one-to-one with a bit in the SB regis-
ter, and acts as a bitwise AND of the SB flags to generate MSS. Bit 6 of
the SRE is undefined—setting it has no e
ff
ect, and reading it always
returns 0. This register is set and queried with the *SRE(?) command.
At power-on, this register is cleared.
SIM918 Precision Current Preamplifier