Anritsu ML2400A Series - Service Request Status (Srq)

2. Re quest data from dis play chan nel 1 by send ing:
O 1
The SRQ will be set with the new read ing which will now be in the out put
buffer ready to be read. The data should now be read so that the MAV bit will
be cleared. If the data is not read, or the out put buffer not cleared, and an -
other re quest for data is made this data will be buff ered af ter the pre vi ous
data.
Get ting a Read ing The 488.2 stan dard re quires that the data can only be read from the de vice af -
ter it has been re quested. Any data re quested from the de vice is made avail able
to be read, and is stored in an out put buffer.
As long as there is data in the out put buffer to be read, the Mes sage AVail able
(MAV) bit in the status byte is set. This bit al lows data to be re quested and, as
soon as the data is avail able, the MAV bit is set, from which a serv ice re quest
can be pro duced (SRQ).
The ML240X al lows this out put buffer to be turned off us ing the BUFF OFF
com mand. In this mode of op er a tion, if a num ber of data re quests are made
with out read ing the data af ter each re quest, only the last data re quested is
avail able. Note that this does not in clude the se rial poll re quest which is han -
dled in de pend ently.
6-8 SERVICE REQUEST
STATUS (SRQ)
The Sys tem Serv ice Re quest Status byte avail able over GPIB by a se rial poll is
de fined as fol lows:
RGH If a sen sor goes over or un der the op er at ing range, this bit is set. This bit can
be used to set an SRQ by set ting the same bit in the SRE reg is ter us ing the
*SRE com mand (page 6-105 ). For more de tail, see the STATUS com mand
(page 6-74 ). This bit can only be cleared by send ing a *CLS com mand (pages
6-12, 6-103 ).
LIM If a chan nel pass/fail limit fails, this bit will be set. This bit can be used to set
an SRQ by set ting the same bit in the SRE reg is ter us ing the *SRE com mand.
For more de tail, see the STATUS com mand. This bit can only be cleared by
send ing a *CLS com mand.
ML2400A OM 6-9
GPIB OPERATION SERVICE REQUEST STATUS (SRQ)