Rohde & Schwarz 1335.8794.02, Руководство пользователя

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Remote control - status reporting system
R&S
®
RTM3000
825 User Manual 1335.9090.02 ─ 09
Table B-9: Bits in the STATus:QUEStionable:MASK register
Bit No. Meaning
0 MASK1
B.4 Application of the status reporting system
The purpose of the status reporting system is to monitor the status of one or several
devices in a measuring system. To do this and react appropriately, the controller must
receive and evaluate the information of all devices. The following standard methods
are used:
●
Service request (SRQ) initiated by the instrument
●
Serial poll of all devices in the bus system, initiated by the controller in order to
find out who sent a SRQ and why
●
Parallel poll of all devices
●
Query of a specific instrument status by means of commands
●
Query of the error queue
B.4.1 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
Figure B-2 , 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 a further register,
the error queue or the output buffer. The
ENABle
parts of the status registers can be
set such that arbitrary bits in an arbitrary status register initiate an SRQ. In order to
make use of the possibilities of the service request effectively, all bits should be set to
"1" in enable registers SRE and ESE.
The SRQ is the only possibility for the instrument to become active on its own. Each
controller program should cause the instrument to initiate a service request if errors
occur. The program should react appropriately to the service request.
B.4.2 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.
Application of the status reporting system