Remote Control
R&S
®
ZNA
748
User Manual 1178.6462.02 ─ 12
7.5.4.3
Parallel Poll
In a parallel poll, up to eight instruments are simultaneously requested by the controller
by means of 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) . 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?
.
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.
7.5.4.4
Query of an Instrument Status
Each part of any status register can be read by means of 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 (e.g.
STATus:OPERation...
)
All queries return a decimal number which represents the bit pattern of the status regis-
ter. This number is evaluated by the controller program.
Queries are usually used after an SRQ in order to obtain more detailed information on
its cause.
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 is keyed 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.
Bits
0
1
2
3
4
5
6
7
...
Weight
1
2
4
8
16
32
64
128
...
Example: The decimal value 40 = 32 + 8 indicates that bits no. 3 and 5 in the status
register (e.g. the QUEStionable status summary bit and the ESB bit in the STB) are
set.
7.5.4.5
Error Queue
Each error state in the instrument leads to an entry in the error queue. The entries of
the error queue are detailed plain text error messages that can be queried via remote
control using
. Each call of
Status Reporting System
