Re: streamdevice to find the last match

[Dirk Zimoch <dirk.zimoch@psi.ch>]

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