Re: problem in communicating to the GPIB device with ASYN4-6

[Emmanuel Mayssat <emmanuel_mayssat@lynceantech.com>]

> > I have declared the command array as follows:
> > {&DSET_SO,GPIBWRITE,IB_Q_LOW,0,"DISPlay:TEXT \"%S""EOSNL, 
> > 0,200,0,0,0,0,0,EOSNL},
> 1) You need to use a lower-case character for the format string.
> 2) As mentioned above, it is better to set the end-of-string values  
> elsewhere.  With these changes the command table entry becomes:
> {&DSET_SO,GPIBWRITE,IB_Q_LOW,NULL,"DISP:TEXT \"%s"",0,200,NULL, 
> 0,0,NULL,NULL,NULL}

Not so long ago, I faced a similar issue.
The serial version of my driver worked well, but that same version using
serial over Ethernet didn't. The problem was traced back to the
terminators...

My understanding is that you have 2 purposes for terminators.
Indeed you really have 2 terminators.
The first one, the output eos, is for the device. That is, you need to
send a correctly formatted command.
Second, the input eos, which is used by asyn to match complete replies.
If the input terminator is never matched by asyn, asyn will keep on
waiting for chars and never forward anything to upper layers (devGpib).
So although you *may think* that the eos are set correctly in your
command table, asyn may never match or pass along any received messages.
Tough!

So if just like me, you want to avoid this one-two punch, from now on
always set the terminators where they are used, i.e. at the asyn level. 

Best of luck with your mental wrestling...

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E