Stanford Research Systems SR844, User Manual

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4-32 Status Registers
SR844 RF Lock-In Amplifier
LIA (Lock-In Amplifier) Status Register: LIAS?, LIAE
bit name set when
0 ULK A reference unlock is detected.
1 FRQ The reference frequency is out of range.
2 –– unused
3 TRG Data storage is triggered.
4 INP The signal input overloads.
5 RSV The IF amplifier overloads.
6 FLT A time constant filter overloads.
7 CHG Reference frequency changed by more than 1%.
8 CH1 Channel 1 display or output overloads.
9 CH2 Channel 2 display or output overloads.
10 OAX Either Aux Input overloads.
11 UAX Ratio input underflows.
12 –– unused
13 –– unused
14 –– unused
15 –– unused
Bits in this register remain set until cleared by reading them or by the
*CLS
command.
Error Status Register: ERRS?, ERRE
bit name set when
0 –– unused
1 BAK Battery backup has failed.
2 RAM The RAM memory test failed.
3 FPG FPGA test failed.
4 ROM The ROM memory test failed.
5 GPB GPIB Fast Data Transfer mode is aborted.
6 DSP The DSP test failed.
7 MTH An internal math error occurred.
Bits in this register remain set until cleared by reading them or by the
*CLS
command.
Using Serial Poll
Except for SRQ, a bit in the Serial Poll Status register is not cleared by serial polling.
When reading the status using a serial poll, the SRQ bit signals that the SR844 is
requesting service. The SRQ bit will be set (1) the first time the SR844 is polled
following a service request. The serial poll automatically clears the service request.
Subsequent polls will return SRQ cleared (0) until another service request occurs. Polling
the status byte and reading it with
*STB?
can return different values for SRQ. When
polled, SRQ indicates a service request has occurred. When read with
*STB?
, SRQ
indicates that an enabled Serial Poll Status bit is set.