Experimental Physics and
Industrial Control System

From: [email protected] [mailto:[email protected]] On Behalf Of Eric Norum
Sent: Tuesday, April 11, 2017 10:00 AM
To: Benoit RAT <[email protected]>
Cc: EPICS mailing list <[email protected]>
Subject: Re: CA client within Asyn

On Apr 11, 2017, at 4:00 AM, Benoit RAT <[email protected]> wrote:

 

Hi everybody,

 

Within my Asyn IOC I need sometime to modify some PV from other IOC. 

I did try to do this using the .db but the task was too complex and I am now trying to setup my own CA client inside Asyn.

As I am using Asyn I have also linked all the callback from CA to the one from Asyn... 

This seems to work more or less but I have some problems with the ca_put.

 

 

quick resume of what I am doing

===========================

 

--------------- # Part 1 (OK)

 

At the setup of the IOC I call:

 

ca_context_create (ca_enable_preemptive_callback);

...

ca_search_and_connect(pvext_write1->name,&(pvext_write1->chan_id),callback_coHaAr,NULL);

ca_search_and_connect(pvext_write2->name,&(pvext_write2->chan_id),callback_coHaAr,NULL);

...

ca_search_and_connect(pvext_writeN->name,&(pvext_writeN->chan_id),callback_coHaAr,NULL);

 

and at the end of the setup I call

 

ca_flush_io()

 

This work fine and after some seconds I enter callback_coHaAr() for each of the CA created.

 

--------------- # Part 2

 

Then at some point in my code, changes of value my internal PV, I modify external PV.

 

status=ca_put_callback (DBR_DOUBLE, pvext_write1->chan_id, &(pvext_write1->val.float64),callback_put,pvext_write1);

status=ca_put_callback (DBR_DOUBLE, pvext_write2->chan_id, &(pvext_write2->val.float64),callback_put,pvext_write2);

....

status=ca_put_callback (DBR_DOUBLE, pvext_writeN->chan_id, &(pvext_writeN->val.float64),callback_put,pvext_writeN);

 

And after all my writes has been put, I call

 

ca_flush_io()

 

 

And this is when sometime my hook callback_put() is correctly called back (Almost 90% the first time)

 

 callback_put() > chid:0x949a3a0 usr:0x94c86a8 (status:x1)

 

But then if I make succesive call, the hook callback_put() might be called back some more time.. and then never

 

 

However If I shutdown the remote IOC, all my callback appears

 

 

If only one was missing, I get on my epicConsole:

 

callback_put() > chid:0x95074c8 usr:0x9535860 (status:xc0) 
callback_coHaAr() > chid:0x95074c8 op:7 (down) 

 

 

If 4 were missing:

 

callback_put() > chid:0x98623f8 usr:0x9890790 (status:xc0)
callback_put() > chid:0x98623f8 usr:0x9890790 (status:xc0)
callback_put() > chid:0x98623f8 usr:0x9890790 (status:xc0)
callback_put() > chid:0x98623f8 usr:0x9890790 (status:xc0)
callback_coHaAr() > chid:0x98623f8 op:7 (down)

 

 

 

Conclusion

===========================

 

I think I am missing something while mixing the epicsThread of asyn and ca, but I really don't know what to try more and I don't find any good examples of ChannelAccess client with thread.

 

• Where could I find a good documentation of ca client?
• Do you think I am missing something?
• Should I use ca_enable_preemptive_callback...? I am not sure that it is what I need within asyn...
• Shouid I use something more than flush_io()...? 
• Should I create a thread for this operation and call ca_pend_event() ... I did try to call ca_pend_event(2) for testing but it doesn't seem to correct my problems.

 

Best,

 

 

 

 

 

--

 

 

Benoit RAT LAMY

fix. (+34) 958 285 024

e-mail: [email protected]

www.sevensols.com 

 

-- 
Eric Norum
[email protected]