Lake Shore 372, Руководство пользователя, Страница: 140 / 214

128 c
HAPTER
6: Computer Interface Operation
Model 372 AC Resistance Bridge and Temperature Controller
firmware filters are settled and a valid control input reading can be taken.
D
Ramp Done—Warm-up Heater (RAMPW), Bit (0): this bit is set when the sample
heater setpoint ramp is completed.
6.2.6.2 Service Request Enable Register
The service request enable register is programmed by the user and determines which
summary bits of the status byte may set bit 6 (RQS/MSS) to generate a service
request. Enable bits are logically ANDed with the corresponding summary bits
(FIGURE 6-3). Whenever a summary bit is set by an event register and its correspond-
ing enable bit is set by the user, bit 6 will set to generate a service request. The Service
Request Enable command (*SRE) programs the service request enable register and
the query command (*SRE?) reads it.
6.2.6.3 Using Service Request (SRQ) and Serial Poll
When a status byte summary bit is enabled by the service request enable register and
goes from 0 to 1, bit 6 (RQS/MSS) of the status byte will be set. This will send a service
request (SRQ) interrupt message to the bus controller. The user program may then
direct the bus controller to serial poll the instruments on the bus to identify which
one requested service (the one with bit 6 set in its status byte).
Serial polling will automatically clear RQS of the status byte register. This allows sub-
sequent serial polls to monitor bit 6 for an SRQ occurrence generated by other event
types. After a serial poll, the same event or any event that uses the same status byte
summary bit, will not cause another SRQ unless the event register that caused the
first SRQ has been cleared, typically by a query of the event register.
The serial poll does not clear MSS. The MSS bit stays set until all enabled status byte
summary bits are cleared, typically by a query of the associated event register
(section 6.2.6.4).
The programming example in TABLE 6-4 initiates an SRQ when a command error is
detected by the instrument.
FIGURE 6-3 Status byte register and service request enable register
RQS
MSS
Generate service
request—reset by
serial poll
Read by *STB?
7 6 5 4 3 2 1 0
RAMPS ESB OVLD ALARM VRM VRC RAMPW Not used
– Bit
– Name
Service request
enable register
*SRE, *SRE?
7 6 5 4 3 2 1 0
RAMPS MSS ESB RQS OVLD ALARM
VRM
VRC RAMPW
– Bit
– Name
Status byte register
*STB?
AND
AND
AND
OR
AND
AND
AND
D AN
From standard event status register