Common Instrument Functions
R&S
®
FPL1000
196
User Manual 1178.3370.02 ─ 03
troller, to which the control program can react appropriately. As evident from
, 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 service request 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.
Use of the command *OPC to generate an SRQ at the end of a sweep
1.
CALL InstrWrite(analyzer, "*ESE 1")
'Set bit 0 in the ESE (Operation
Complete)
2.
CALL InstrWrite(analyzer, "*SRE 32")
'Set bit 5 in the SRE (ESB)
3.
CALL InstrWrite(analyzer, "*INIT;*OPC")
' Generate an SRQ after
operation complete
After its settings have been completed, the instrument generates an SRQ.
A detailed example for a service request routine is provided in
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.
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,
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 using the command
The instrument first has to be set for the parallel poll using the command
PPC
. This
command allocates a data line to the instrument and determines whether the response
is to be inverted. The parallel poll itself is executed using
PPE
.
Network and Remote Operation
