Experimental Physics and
Industrial Control System

[...]
	switch(at) {
[...]
	case gddAppType_ackt:
	case gddAppType_acks:
		docallback = GATE_NOCALLBACK;
		// Fall through
	default:
[...]
			caStatus stat = pv->put(&dd, docallback);
			if(stat != S_casApp_success) return stat;

			if(docallback) {
				// Start a pending write
#if DEBUG_GDD
				fflush(stderr);
				printf("pending_write\n");
				fflush(stdout);
#endif
				pending_write = new gatePendingWrite(*this,ctx,dd);
				if(!pending_write) return S_casApp_noMemory;
				else return S_casApp_asyncCompletion;
			} else {
				return S_casApp_success;
			}

if (ctx.getMsg()->m_cmmd == CA_PROTO_WRITE_NOTIFY) {
  docallback == GATE_DOCALLBACK;
} else {
  docallback == GATE_NOCALLBACK;
}

I can confirm that the problem appears isolated to the scaler record CNT
field and not enums in general.

It looks like Tim's ca_put_callback theory may be correct. Is there a
Gateway expert out there who can confirm this? How are writes done from
the Gateway. Does it always use ca_put_callback regardless of how the
put reached the gateway?

Thanks for everyones responses on this.

Pete Leicester
Diamond

-----Original Message-----
From: Tim Mooney [mailto:[email protected]] Sent: 28 March 2006 21:07
To: Leicester, PJ (Pete)
Cc: [email protected]
Subject: Re: gateway enum writes


Leicester, PJ (Pete) wrote:

I am getting some strange behaviour when writing enumerations through
the Gateway (version 2.0.0.0 on 3.14.8.2 and RedHat Enterprise 4).

The problem first showed itself in edm when pressing a button on a edm
screen to send the value resulted in the following error:

   CA.Client.Exception...............................................
       Warning: "Virtual circuit unresponsive"
       Context: "diamrs0005l.diamond.ac.uk:6064"
       Source File: ../tcpiiu.cpp line 896
       Current Time: Tue Mar 28 2006 16:19:01.334736000
   ..................................................................

I did some further tests using caput with similar results:

   [pjl45@pc0005 pjl45]$ caput  -w15 GDA:scaler2.CNT Count
   Old : GDA:scaler2.CNT                Done
   Read operation timed out: PV data was not read.
   New : GDA:scaler2.CNT
   CA.Client.Exception...............................................
       Warning: "Virtual circuit disconnect"
       Context: "op=0, channel=GDA:scaler2.CNT, type=DBR_TIME_STRING,
count=1, ctx="diamrs0005l.diamond.ac.uk:6064""
       Source File: ../getCopy.cpp line 82
       Current Time: Tue Mar 28 2006 17:04:24.488496000
.
Despite the above error message the write does actually reach the IOC.
However if I now try the change the value back as follows:

   [pjl45@pc0005 pjl45]$ caput  -w15 GDA:scaler2.CNT Done
   Old : GDA:scaler2.CNT                Count
   Read operation timed out: PV data was not read.
   New : GDA:scaler2.CNT
   CA.Client.Exception...............................................
       Warning: "Virtual circuit disconnect"
       Context: "op=0, channel=GDA:scaler2.CNT, type=DBR_TIME_STRING,
count=1, ctx="diamrs0005l.diamond.ac.uk:6064""
       Source File: ../getCopy.cpp line 82
       Current Time: Tue Mar 28 2006 17:22:36.167980000
   ..................................................................

I get an error again however this time the 'Done' value gets written to
the IOC exactly ONE MINUTE after I entered the caput command. This is long after the caput command has timed out so it appears the gateway

is

responsible for the delay?

Has anyone any idea what may be happening? Is there a 60 second timeout
in CA or the gateway which may give a clue as to what I am seeing?

(For the record this test was done with a very lightly loaded test
gateway serving only 20 or so PV's. Also using caput -w70 results in

the

same timeouts)

Do you get this kind of result with *all* enum fields that you write to
through the gateway, or only this one?  The scaler record's CNT field is
different from other enum's in that it starts an operation that may take
a long time to complete.  I don't know what the gateway is using to do
put's, but if it should happen to be ca_put_callback(), the gateway may
be waiting for a callback that will come only after the scaler has
finished counting.

--
Dr. Dirk Zimoch
Swiss Light Source
Paul Scherrer Institut
Computing and Controls
phone +41 56 310 5182
fax   +41 56 310 4413

Replies:

RE: gateway enum writes Jeff Hill

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RE: gateway enum writes Leicester, PJ (Pete)

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