Remote Control Basics
R&S
®
SMB100A
276
Operating Manual 1407.0806.32 ─ 21
Example:
Use command
*OPC
to generate an SRQ .
*ESE 1
- set bit 0 of ESE (Operation Complete)
*SRE 32
- set bit 5 of SRE (ESB).
After its settings have been completed, the instrument generates an SRQ.
The SRQ is the only possibility for the instrument to become active on its own. Each
controller program should set the instrument such that a service request is initiated in
the case of malfunction. The program should react appropriately to the service request.
6.5.7.2
Serial Poll
In a serial poll, just as with command
*STB
, the status byte of an instrument is queried.
However, the query is realized via interface messages and is thus clearly faster.
The serial poll method is defined in IEEE 488.1 and used to be the only standard pos-
sibility for different instruments to poll the status byte. The method also works for
instruments which do not adhere to SCPI or IEEE 488.2.
The serial poll is mainly used to obtain a fast overview of the state of several instru-
ments connected to the controller.
6.5.7.3
Query of an instrument status
Each part of any status register can be read using queries. There are two types of
commands:
●
The common commands
*ESR?
,
*IDN?
,
*IST?
,
*STB?
query the higher-level
registers.
●
The commands of the
STATus
system query the SCPI registers
(
STATus:QUEStionable
...)
The returned value is always a decimal number that represents the bit pattern of the
queried register. This number is evaluated by the controller program.
Queries are usually used after an SRQ in order to obtain more detailed information on
the cause of the SRQ.
6.5.7.4
Error Queue
Each error state in the instrument leads to an entry in the error queue. The entries of
the error queue are detailed plain text error messages that can be looked up in the
Error Log or queried via remote control using
SYSTem:ERRor[:NEXT]?
. Each call of
SYSTem:ERRor[:NEXT]?
provides one entry from the error queue. If no error mes-
sages are stored there any more, the instrument responds with 0, "No error".
The error queue should be queried after every SRQ in the controller program as the
entries describe the cause of an error more precisely than the status registers. Espe-
cially in the test phase of a controller program the error queue should be queried regu-
Status Reporting System
