Experimental Physics and
Industrial Control System

Wesley Moore <[email protected]> · Fri, 23 Aug 2013 09:20:54 -0400 (EDT)

Hey Dehong,

I was thinking along the lines of Dirk's response (leave InTerminator = CR LF).  However, leaving InTerminator=; have you tried using @mismatch to instead parse the double message?

Wesley

----- Original Message -----
> From: "Dirk Zimoch" <[email protected]>
> To: "Dehong Zhang" <[email protected]>
> Cc: [email protected]
> Sent: Friday, August 23, 2013 3:55:37 AM
> Subject: Re: streamdevice to find the last match
> 
> Hello Dehong,
> 
> Is your record "I/O Intr"? I assume so because your STATUS protocol
> does
> not have any out command.
> 
> In that case and if you set InTerminator  = CR LF, you should
> actually
> get 2 messages and the record should be processed twice. Thus at the
> end, your record will have the correct value.
> 
> Skipping intermediate results is tricky on the protocol level,
> because
> how should StreamDevice know that no more input is about to come?
> What
> if the gap between the messages is sometimes so big, that you
> actually
> get 2 messages?
> 
> But In case you really always get a double message as below and want
> to
> read the second value only you can skip the first one:
> 
> in "BOS%*d,P=%*dEOS\r\nBOS%d,P=%(otherrecord)dEOS\r\n"
> 
> In case you may have an arbitrary number of messages connected and
> always want to skip all but the last, things become tricky. I have to
> make up a PCRE. The idea is to do a greedy search for everything up
> to
> "BOS" and then read the data. I will send you the PCRE later.
> 
> Dirk
> 
> 
> 
> On 22.08.2013 21:17, Zhang, Dehong wrote:
> > Hi Dirk and Friends,
> >
> > (Sorry if you get this 2 times.  I had a wrong address with my
> > previous send)
> >
> > I run into 2 little problems: I wait for the hardware to send a
> > message like
> > "BOS123456,P=987654EOS\r\n".
> > Here BOS is my starting label and EOS the ending label.
> >
> > Due to timing, which I cannot control, sometimes I would receive 2
> > messages
> > together, like:
> > "BOS123456,P=987654EOS\r\nBOS345,P=987649EOS\r\n".
> > Here the first one was sent when the state was still changing, the
> > second one
> > was sent when the state stablizes.  But the time in between is so
> > short that the
> > 2 messages just come out as one.  How can I skip the first match,
> > only get the
> > second/last match?
> >
> > My protocal is like:
> > InTerminator  = CR;
> > OutTerminator = CR LF;
> > ReplyTimeout  = 800;
> > ReadTimeout   = 100;
> > WriteTimeout  = 100;
> > ExtraInput    = Ignore;
> >
> > # Reports from the controller
> > STATUS  { ReplyTimeout = 50; ReadTimeout = 10; InTerminator =; in
> > "%.1/BOS([0-9,P=]*EOS)/"; }
> >
> > I tried to use the "$" anchor, but cannot get it to work -- maybe
> > because "$" is a special
> > character in streamdevice.
> >
> > Related to this, sometimes the time in between is not so short that
> > the 2 messages
> > do come out separately, but the time in between is short enough so
> > that my stringin
> > record misses the second message.  How can I avoid this?  Tune the
> > ReplyTimeout,
> > ReadTimeout and InTerminator?
> >
> > Thank you for your advice.  Best regards,
> > Dehong
> >
> 
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System