Experimental Physics and
Industrial Control System

"Lucock, Richard M" <[email protected]> · Mon, 04 Jun 2018 15:30:39 +0100

Hi,

	I am having problems parsing data from a serial device (ie
obtained using asyn & stream). The normal protocol is to send a
message (with checksum), wait for an ACK character, then read the
reply (which has a checksum).

If I read the ACK and the reply on one line, using the protocol below:

   read_version {
      out STX, "001?f" ETX, "%<xor8ff>";
      in ACK, STX, "001 f%[^\003]", ETX, "%<xor8ff>";
   }

then I get the correct data into my 'stringin' record, but the shell
reports that the checksum is wrong (presumably because the ACK has
been included in the calculation). If I separate out the ACK and the
reply inputs:

   read_version {
      out STX, "001?f" ETX, "%<xor8ff>";
      in ACK;
      in STX, "001 f%[^\003]", ETX, "%<xor8ff>";
   }

then the shell reports no errors, but nothing is placed in my
'stringin' record.

The messages have no terminators, which I guess is part of the
problem. I have tried playing about with 'extrainput', 'maxinput' and
'wait', with no luck. Does anyone have any suggestions for dealing
with this ?

Thanks,
	Richard

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System