Rohde & Schwarz SMC100A, Руководство по эксплуатации

Страница: 218 / 363

Remote Control Basics
R&S
®
SMC100A
201 Operating Manual 1411.4060.32 ─ 04
6.5.5.1 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. An SRQ is always initiated if one or several of
bits 2, 4 or 5 of the status byte are set and enabled in the SRE. Each of these bits com-
bines the information of the error queue or the output buffer. In order to use the possi-
bilities 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 .
*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.
6.5.5.2 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.
6.5.5.3 Parallel Poll
In a parallel poll, up to eight instruments are simultaneously requested by the controller
using a single command to transmit 1 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) which is ANDed with the STB
bit by bit, considering bit 6 as well. This register is ANDed with the STB bit by bit, con-
sidering 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 using the command
​
*IST
​
.
The instrument first has to be set for the parallel poll using the command
PPC
. This com-
mand allocates a data line to the instrument and determines whether the response is to
be inverted. The parallel poll itself is executed using
PPE
.
Status Reporting System