Rohde & Schwarz SMB100A - Error Queue; Reset Values of the Status Reporting System; Query of an Instrument Status; Serial Poll

Remote Control Basics
R&S
®
SMB100A
240Operating Manual 1407.0806.32 ─ 13
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 possi-
bility for different instruments to poll the status byte. The method also works for instru-
ments 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 instruments
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 com-
mands:
●
The common commands *ESR?, *IDN?, *IST?, *STB? query the higher-level reg-
isters.
●
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]? or
SYSTem:ERRor:ALL?. Each call of SYSTem:ERRor[:NEXT]? provides one entry from
the error queue. If no error messages 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. Especially
in the test phase of a controller program the error queue should be queried regularly since
faulty commands from the controller to the instrument are recorded there as well.
6.5.8 Reset Values of the Status Reporting System
The following table contains the different commands and events causing the status
reporting system to be reset. None of the commands, except of *RST and
Status Reporting System