RQC
Re quest Con trol. GPIB con trol lers only.
OPC
Op era tion Com plete. When a pro gram mes sage that in cludes the *OPC com -
mand has been com pleted, and the GPIB in ter face is idle, with any re sponses
read out of the out put buffer this bit is set. For ex am ple, if the last com mand in a
con figu ra tion se quence is *OPC, the OPC bit in the event status reg is ter will be
set when that con figu ra tion list has been com pleted.
Also refer to Fig ure 6-2, page 6-13 , IEEE 488.2 Stan dard Status Struc tures .
If an event causes a bit in the ESR to be set and the cor re spond ing bit in the
Event Status En able byte (ESE) is set, the ESB bit in the status byte will be
set. This can cause an SRQ (see Sec tion 6-8 ) if the ESB bit in the Status Reg is -
ter En able byte (SRE) is set. For ex am ple, to get an SRQ on an un rec og nized
com mand do the fol low ing:
1. Set the CMD bit in the event status en able byte, and set the ESB bit in the
status reg is ter en able byte. Send:
*ESE 32;*SRE 32
2. Now if an un rec og nized com mand is sent to the ML2400A, an SRQ will be
given. Send:
asdf
An SRQ will be in di cated.
3. To clear the SRQ do a se rial poll, this should re turn the deci mal value 96, bit 6
for the SRQ and bit 5 for the ESB. The SRQ will be cleared.
4. To read the Event Status Reg is ter (ESR), send:
*ESR?
This will put 32 (or 160 if PON is set) in the out put buffer to be read.
Mes sage
Avail able
Bit (MAV)
This bit is set if there is any data in the out put buffer wait ing to
be read, and can be used to en sure that only the lat est read ing is
used. Upon re ceiv ing a re quest for data, the next read ing taken is
put in the out put buffer. The data in the out put buffer should al -
ways be read when data is avail able to en sure that old data is
never left be hind. The ad van tage of this method is that if the
MAV bit is not set, the con trol ler can not read old data, there fore
data can only be read af ter it has been re quested. Ex am ple:
1. In Read out dis play with the out put buffer empty and the MAV bit not set, con -
fig ure the ML2400A to give an SRQ on data be com ing avail able by set ting bit 4
in the Status Reg is ter En able byte (SRE):
*SRE 16
6-8 ML2400A OM
USING 488.2 GPIB GPIB OPERATION
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