Experimental Physics and
Industrial Control System

Jameson Graef Rollins <[email protected]> · Fri, 29 Dec 2017 14:36:10 -0800

Hi, Xiaoqiang.  Where you not able to verify this problem?  This should
be independent from the other issue I reported.

I still see the same problem with the head of master (1f0a509).  I'm
using EPICS 3.15.5.

jamie.

On Wed, Dec 27 2017, Jameson Graef Rollins <[email protected]> wrote:
> Hi, Xiaoqiang et. al.  I'm seeing some behavior in pcaspy 0.7.0 that I'm
> not understanding, and I'm hoping you can help me figure out what's
> going on.
>
> I have a trivial test pcaspy IOC (code attached) serving a single
> channel "TEST:A".  After starting the IOC I run camonitor on the
> channel:
>
> $ camonitor TEST:A
> TEST:A                         2017-12-27 19:15:42.991145 0
>
> If I then put the *same* initial value into the channel...
>
> $ caput TEST:A 0
> Old : TEST:A                         0
> New : TEST:A                         0
> $
>
> ...I see an update:
>
> guard-test> camonitor TEST:A
> TEST:A                         2017-12-27 19:15:42.991145 0  
> TEST:A                         2017-12-27 19:15:50.661466 0  
>
> Additional puts with the same value show no more spurious updates.  So
> this only happens immediately after initialization.
>
> This is contrary to the behavior that I now expect, whereby there would
> never be external updates if the value was not changing.  Can you help
> me understand what's going on?
>
> Basically I'm looking for the best way to get consistent behavior out of
> the pcaspy driver, either where puts always show updates even if the
> value is the same, or that puts of the current value do not ever show
> updates.  How can I achieve this?
>
> Thanks in advance for any help.
>
> jamie.
>
>
> #!/usr/bin/env python
>
> import sys
> import pcaspy
>
> prefix = 'TEST:'
> pvdb = {
>     'A': {
>         'prec': 0
>     },
> }
>
> class DummyDriver(pcaspy.Driver):
>     pass
>
> server = pcaspy.SimpleServer()
> server.createPV(prefix, pvdb)
> driver = DummyDriver()
>
> for k in pvdb:
>     driver.setParamStatus(k, pcaspy.Severity.NO_ALARM, pcaspy.Severity.NO_ALARM)
> driver.updatePVs()
>
> while True:
>     server.process(0.1)

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System