
Remote Control
R&S
®
RTM20xx
265
User Manual 1317.4726.02 ─ 01
The output buffer contains the messages the instrument returns to the controller. It
is not part of the status reporting system but determines the value of the
MAV
bit in
the
STB
and thus is represented in the overview.
All status registers have the same internal structure.
SRE, ESE
The service request enable register
SRE
can be used as
ENABle
part of the
STB
if the
STB
is structured according to SCPI. By analogy, the
ESE
can be used as the
ENABle
part of the
ESR.
15.1.6.3
Contents of the Status Registers
In the following sections, the contents of the status registers are described in more detail.
Status Byte (STB) and Service Request Enable Register (SRE)
The
STatus Byte
(STB) is already defined in IEEE 488.2. It provides a rough overview
of the instrument status by collecting the pieces of information of the lower registers. A
special feature is that bit 6 acts as the sum bit of the remaining bits of the status byte.
The STB can thus be compared with the
CONDition
part of an SCPI register and
assumes the highest level within the SCPI hierarchy.
The STB is read using the command
The
STatus Byte
(STB) is linked to the
Service Request Enable
(SRE) register.
Each bit of the STB is assigned a bit in the SRE. Bit 6 of the SRE is ignored. If a bit is set
in the SRE and the associated bit in the STB changes from 0 to 1, a service request
(SRQ) is generated. The SRE can be set using the command
and read using the
command
*SRE?
.
Table 15-3: Meaning of the bits used in the status byte
Bit No.
Meaning
0...1
Not used
2
Error Queue not empty
The bit is set when an entry is made in the error queue. If this bit is enabled by the SRE, each
entry of the error queue generates a service request. Thus an error can be recognized and speci-
fied in greater detail by polling the error queue. The poll provides an informative error message.
This procedure is to be recommended since it considerably reduces the problems involved with
remote control.
3
QUEStionable status register summary bit
The bit is set if an
EVENt
bit is set in the
QUEStionable
status register and the associated
ENABle
bit is set to 1. A set bit indicates a questionable instrument status, which can be specified
in greater detail by querying the
STATus:QUEStionable
status register.
4
MAV bit (message available)
The bit is set if a message is available in the output queue which can be read. This bit can be used
to enable data to be automatically read from the instrument to the controller.
Basics