Status Byte (Sb); Service Request Enable (Sre) - Stanford Research Systems SIM918 Operating And Service Manual

3.5 Status Model

3.5.1 Status Byte (SB)

3.5.2 Service Request Enable (SRE)

SIM918 Precision Current Preamplifier
At power-on, all status registers are cleared.
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 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.
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 ect, and reading it always
returns 0. This register is set and queried with the *SRE(?) command.
At power-on, this register is cleared.
3 – 25