Remote Control Basics
R&S
®
SMB100A
273
Operating Manual 1407.0806.32 ─ 21
The instrument automatically generates the sum bit for each register. Thus an event
can lead to a service request throughout all levels of the hierarchy.
6.5.3 Status Byte (STB) and Service Request Enable Register (SRE)
The
STatus Byte
(STB) is already defined in IEEE 488.2. It provides a rough over-
view of the instrument status by collecting the pieces of information of the lower regis-
ters. A special feature is that bit 6 acts as the sum bit of the remaining bits of the status
byte.
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 6-3: 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
specified in greater detail by polling the error queue. The poll provides an informative error mes-
sage. 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 speci-
fied 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.
5
ESB bit
Sum bit of the event status register. It is set if one of the bits in the event status register is set
and enabled in the event status enable register. Setting of this bit indicates a serious error which
can be specified in greater detail by polling the event status register.
6
MSS bit (master status summary bit)
The bit is set if the instrument triggers a service request. This is the case if one of the other bits
of this registers is set together with its mask bit in the service request enable register SRE.
7
STATus:OPERation
status register summary bit
The bit is set if an
EVENt
bit is set in the
OPERation
status register and the associated
ENABle
bit is set to 1. A set bit indicates that the instrument is just performing an action. The
type of action can be determined by querying the
STATus:OPERation
status register.
Status Reporting System
