User manual

84 Relay Multiplexer Command Reference Chapter 3
STATus
The STATus subsystem reports the bit values of the Operation Status
Register. It also allows you to unmask the bits you want reported from the
Standard Event Register and to read the summary bits from the Status
Byte Register.
Subsystem Syntax STATus
:OPERation
:CONDition?
:ENABle <number>
:ENABle?
[:EVENt?]
:PRESet
The STATus system contains four registers, two of which are under IEEE
488.2 control: the Standard Event Status Register (*ESE?) and the
Status Byte Register (*STB?). The operational status bit (OPR), service
request bit (RQS), standard event summary bit (ESB), message
available bit (MAV) and questionable data bit (QUE) in the Status Byte
Register (bits 7, 6, 5, 4 and 3 respectively) can be queried with the *STB?
command.
Use the *ESE? command to query the “unmask” value for the Standard
Event Status Register (the bits you want logically OR’d into the summary
bit). The registers are queried using decimal weighted bit values. The
decimal equivalents for bits 0 through 15 are included in Figure 3-1.
A numeric value of 256 executed in a STAT:OPER:ENABle <number>
command allows only bit 8 to generate a summary bit. The decimal value
for bit 8 is 256.
The decimal values are also used in the inverse manner to determine
which bits are set from the total value returned by an EVENt or
CONDition query. The multiplexer driver exploits only bit 8 of Operation
Status Register. This bit is called the scan complete bit which is set
whenever a scan operation completes. Since completion of a scan
operation is an event in time, bit 8 will never appear set when
STAT:OPER:COND? is queried. However, you can find bit 8 set with the
STAT:OPER:EVEN? query command.