Control Functions
PSI BOX PLUS+ Reference
WAIT SRQ.
Wait Till Srq Is True.
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Purpose.
The PSI BOX waits till the SRQ line is asserted true
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by a device.
The WAIT SRQ command is used to allow the PSI BOX
to wait till a device requests service. This usually signals that the
device has some new data ready or has finished completing
some pre programmed job. The PSI BOX will wait for SRQ
until timeout or until the SRQ is true. If you want the PSI BOX
to wait indefinitely for SRQ then you should disable the timeout
using the NO TO command.
Once the SRQ line has been asserted true you should perform a
serial poll, using the SPOLL command, to determine which
device has requested service and exactly why.
On entry the PSI BOX checks the state of SRQ and if it is
already asserted true then it exits the routine immediately.
Otherwise it waits till the SRQ changes from the false to the
true state. If timeouts are enabled then the PSI BOX will exit
the WAIT SRQ routine if SRQ has not been asserted within the
timeout period.
Format.
WAIT SRQ
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Params.
None.
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Returns.
None.
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Example.
________
_
BUS TO 1 WAIT SRQ
:REM WAIT secs for SRQ
BUS NO TO WAIT SRQ
:REM WAIT indefinitely
Bus Activity.
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_
None.
Chapter 8
Page 163
