Remote control
R&S
®
ZNB/ZNBT
838
User Manual 1173.9163.02 ─ 62
The parallel poll method is used to find out quickly which one of the instruments con-
nected to the controller has sent a service request. To this effect, SRE and PPE must
be set to the same value.
6.5.4.4
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 (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 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.
6.5.4.5
Error queue
Each error state in the instrument leads to an entry in the error queue, whose current
number of entries can be queried using
. The entries of the
error queue are detailed plain text error messages that can be queried via remote con-
trol using
or
SYSTem:ERRor[:NEXT]?
provides one entry from the error queue. If no error mes-
sages are stored there any more, the instrument responds with
0, "No error"
.
The error queue should be queried after every SRQ in the controller program as the
entries describe the cause of an error more precisely than the status registers. Espe-
cially in the test phase of a controller program the error queue should be queried regu-
larly since faulty commands from the controller to the instrument are recorded there as
well.
Status reporting system
