107
C.4
Status Byte
The Status Byte register is used to record a summary of current system
conditions for the status reporting system. It is returned to the controller
when a serial poll of the 2835-C is conducted or when the *STB? query is
issued.The register is bit mapped, meaning that each condition is represented
by a bit. When a bit is set, or has a value of 1, then the condition is true. The
bits are cleared based on the conditions described for each bit.
The Service Request Enable register is used to define the conditions that will
generate a IEEE 488.1 <SRQ>. When an event occurs that causes a bit to be set
in the Status Byte register and it’s corresponding bit is set in the Service
Request Enable register, then a <SRQ> will be generated.
The Service Request Enable Register is configured by using the *SRE common
command.
The Parallel Poll Enable Register is used with the Status Byte to generate the
<IST> message. If any bit is set in the Status Byte and it’s corresponding bit is
set in the Parallel Poll Enable Register, then the <IST> message is set true (a
value of one). Otherwise the <IST> message is set false (a value of zero).
When a parallel poll is conducted with the 2835-C configured to respond to it,
the <IST> message is compared to the <S BIT> (sense bit). If they are the same
then the configured data line will be driven true in response to the parallel poll.
Both the <S BIT> and the data line driven during a parallel poll can be selected
by the IEEE 488.1 parallel poll remote configuration command.
The Parallel Poll Enable Register is configured by using the *PRE command.
The Status Byte Register is described below.
Status Byte
bit 7: Error Queue
A one in this bit indicates that the error queue is not empty (see the
*ERR? query). The *CLS command will empty the error queue and, as a
result, this bit.
bit 6: Service Request/Master Summary Status
When the status byte is read by means of a serial poll, this bit is set
when the 2835-C is requesting service.
When the status byte is read by means of the *STB? query, this bit will
be set if any bit in the status byte is set and its corresponding bit is set
in the Service Request Enable Register.
bit 5: Event Status Byte
The Event Status Byte bit is set when a bit in the Standard Event Status
register is set and its corresponding bit in the Standard Event Enable
register is set. The *CLS command or *ESR? query will clear the Stan-
dard Event Status register and, as a result, this bit.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
