R&S ESR Series User Manual page 593

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R&S ESR
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 *IST?.
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.
The parallel poll method is mainly used to find out quickly which one of the instruments
connected to the controller has sent a service request. To this effect, SRE and PPE
must be set to the same value.
Query of an instrument status
Each part of any status register can be read using queries. There are two types of
commands:
●
The common commands *ESR?, *IDN?, *IST?, *STB? query the higher-level
registers.
●
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.
Decimal representation of a bit pattern
The STB and ESR registers contain 8 bits, the SCPI registers 16 bits. The contents of
a status register are specified and transferred as a single decimal number. To make
this possible, each bit is assigned a weighted value. The decimal number is calculated
as the sum of the weighted values of all bits in the register that are set to 1.
User Manual 1175.7068.02 ─ 12
Remote Control
Remote Control - Basics
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