Status Reporting System R&S SMB
1407.0806.32 5.26 E-2
Application of the Status Reporting System
In order to effectively use the status reporting system, the information contained there must be
transmitted to the controller and further processed. There are several methods, which are outlined in
the following.
Service Request
Under certain circumstances, the instrument can send a service request (SRQ) to the controller. Usually
this service request initiates an interrupt at the controller, to which the control program can react
appropriately. As evident from section "Overview of the Status Register", an SRQ is always initiated if
one or several of bits 2, 3, 4, 5 or 7 of the status byte are set and enabled in the SRE. Each of these
bits combines the information of the error queue or the output buffer. In order to use the possibilities of
the service request effectively, all bits should be set to "1" in the enable registers SRE and ESE.
Example:
Use command "*OPC" to generate an SRQ
! CALL IBWRT(generator%, "*ESE 1") set bit 0 of ESE (Operation Complete)
! CALL IBWRT(generator%, "*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.
Serial Poll
In a serial poll, just as upon the command "*STB", the status byte of an instrument is queried. However,
the query is made via interface messages and is thus clearly faster. The serial-poll method has already
been defined in IEEE 488.1 and used to be the only standard possibility 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 VISUAL BASIC command for executing a serial poll is "IBRSP()". The serial poll is mainly used to
obtain a fast overview of the state of several instruments connected to the IEC/IEEE bus or via the
Ethernet .
Parallel Poll
In a parallel poll, the controller uses a single command to request up to eight instruments to transmit
one bit of information each on the data lines, i.e., to set the data line allocated to each instrument to a
logical "0" or "1". In addition to the SRE register, which determines the conditions under which an SRQ
is generated, there is a parallel poll enable register (PPE). This register is ANDed with the STB bit by
bit, considering bit 6 as well. The results are ORed, the result is possibly inverted and then sent as a
response to the parallel poll of the controller. The result can also be queried without parallel poll by
means of the command "*IST?".
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