PPC3™ OPERATION AND MAINTENANCE MANUAL
© 2002-2007 DH Instruments, a Fluke Company Page 114
4.5 STATUS REPORTING SYSTEM
The PPC3 status reporting system is used to track and report system status and errors. It follows the
model of the IEEE Std 488.2 and works for the COM1 and the IEEE-488 port with slight differences.
The PPC3 can be programmed to respond to various status conditions by asserting the SRQ of the IEEE-
488 interface. The COM1 port cannot be supported in such a way, so polling must be used.
4.5.1 ERROR QUEUE
The PPC3 keeps track of remote errors by using an error queue. If an error occurs, it is pushed
onto the Error Queue. If you are using the COM1 port, the error number is immediately
replied in the form “ERR#nn where nn is the error code from 0 to 99. The “ERR?” (or “ERR”)
query can then be used to pull the error from the Error Queue in it’s descriptive text format.
If you are using the enhanced program message format, the Error Queue will accumulate
errors until full unless they are pulled from the queue. If you are using the classic program
format, the Error Queue is cleared every time a new program message is received.
4.5.2 STATUS BYTE REGISTER
The PPC3 contains an 8 bit Status Byte Register that reflects the general status of the PPC3.
Table 18. 8 Bit Status Byte Register
OPER
(128)
RQS/MSS
(64)
ESB
(32)
MAV
(16)
N/A
(8)
ERROR
(4)
N/A
(2)
RSR
(1)
This register is affected by the PPC3 reply output queue, the Error Queue, the Standard
Event Status register and the Ready Event Status register.
Status Byte Register
(“
∗STB?” or ”∗SRE n”)
OPER
(128)
RQS/MSS
(64)
Standard Event Status Register
(“∗ESR?” or “∗ESE n”)
ESB
(32)
←←←
PON
(128)
URQ
(64)
CMD
(32)
EXE
(16)
DDE
(8)
QYE
(4)
RQC
(2)
OPC
(1)
MAV
(16)
←←←
OUTPUT
QUEUE
N/A
(8)
ERROR
(4)
←←←
ERROR
QUEUE
N/A
(2)
Ready Event Status Register
(“RSR?” or ” RSE n”)
RSR
(1)
←←←
N/A
(128)
N/A
(64)
N/A
(32)
N/A
(16)
N/A
(8)
MEAS
(4)
NRDY
(2)
RDY
(1)
Figure 10. Status Register Schematic
The Status Byte Register can be read using the “*STB?” query, or by performing a serial poll
on the IEEE-488 bus. If you read this using a serial poll then Bit 6 is the RQS. If the
“*STB?” query is used, then bit 6 is the MSS bit. All of the other bits are common to both types
of query.
Each of these status bits can cause a SRQ to occur. The Service Request Enable Register
(“*SRE” program message ) determines which of these flags are able to assert the SRQ line.
This enable register has a matching set of bits that each will enable the designated bit to
cause a SRQ, except for the RQS/MSS bit(s) which cannot cause a SRQ. If you set this
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