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as long as there is unfetched data in any
of the status event registers.
–
The Requested Service bit, RQS, is set true
when a service request has been signalled.
If you read the status byte via a Serial Poll,
bit 6 represents RQS. Reading the status
byte with a serial poll will set the RQS bit
false, showing that the status byte has been
read.
–
The Master Summary Status bit, MSS, is
set true if any of the bits that generates
SRQ is true. If you read the status byte us
-
ing *STB?, bit 6 represents MSS. MSS re
-
mains true until all event registers are
cleared and all queues are empty.
Setting up the Counter to
Report Status
Include the following steps in your pro-
gram when you want to use the status re-
porting in CNT-8X:
–
*CLS Clears all event registers and the er-
ror queue
–
*ESE <bit mask> Selects what condi-
tions in the Standard Event Status register
should be reported in bit 5 of the status
byte
–
:STATus:OPERation:ENABle <bit
mask> Selects which conditions in the
Operation Status register should be re
-
ported in bit 7 of the status byte
–
:STATus:QUEStionable:ENABle
<bit mask> Selects which conditions in
the Questionable Status register should be
reported in bit 3 of the status byte
–
:STATus:DREGister0:ENABle
<bit mask> Selects which conditions
in Device Register 0 should be reported in
bit 0 of the status byte
–
*SRE <bit mask> Selects which bits
in the status byte should cause a Service
Request
A programming example using status re
-
porting is available in the Programming
Examples in chapter 4.
Reading and Clearing Status
n
Status Byte
As explained earlier, you can read the sta
-
tus byte register in two ways:
Using the Serial Poll (IEEE-488.1 de
-
fined).
–
Response:
–
Bit 6: RQS message, shows that the
counter has requested service via the
SRQ signal.
–
Other bits show their summary mes-
sages
–
A serial poll sets the RQS bit
FALSE, but does not change other
bits.
Using the Common Query *STB?
–
Response:
–
Bit 6: MSS message, shows that
there is a reason for service request.
–
Other bits show their summary mes
-
sages.
–
Reading the response will not alter
the status byte.
n
Status Event Registers
You read the Status Event registers with
the following queries:
6-18 Status Subsystem
Using the Subsystems