Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Tue, 14 Jul 2009 12:15:42 -0500

Hi Stephanie,

I think you should be fine.  Many TCP devices don't sent terminators,
unlike their serial counterparts.  In your st.cmd file you just don't
define an input or output EOS for that driver, and you don't put a
terminator in your protocol file.  The TCP driver does not loop waiting
for maxChars, it just reads the message.  TCP delivers "complete"
messages, so you will get the complete response, not just a partial
response.

Mark

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Allison, Stephanie
Sent: Tuesday, July 14, 2009 11:58 AM
To: Epics Questions
Subject: When an external device does not provide termination on TCP
ASCIIstream replies

Hello,

We're testing a Genesys power supply (provided by Lambda-TDK) to which
the vendor has added a TCP interface (I believe specifically by request
of EPICS sites).  Burkhard Kolb at GSI provided me the protocol file for
stream/asyn support for this type of device (thanks!).  However, the
firmware has changed recently and one change is to remove the terminator
from the reply strings.  Some replies are fixed-length so I can change
the protocol file for these (to use maxInput).  However some replies are
not fixed-length and I need to find support for those - I do not want to
rely on a timeout to know that the reply is finished.  The vendor has
suggested that (1) I assume the reply will never get fragmented and just
allocate 100 bytes and take whatever I get and (2) block on the receive
(which is not an option for an IOC).

Does anybody have experience with such devices (TCP ASCII SCPI commands
that have no reply terminators and no fixed-length reply strings) and
can recommend a solution?

Thank you,
Stephanie Allison
SLAC National Accelerator Lab

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System