Experimental Physics and
Industrial Control System

Wang Xiaoqiang <[email protected]> · Mon, 20 Nov 2017 11:02:56 +0100

Hi Jamie,

The UDF (UnDeFined) alarm and INVALID severity is to indicate the values

are default values, have not got updated by the driver. This is the same

behavior as the EPICS database gets initialized on start-up.

Calling setParamStatus to clear the alarm status is all correct. It is

then necessary to call driver.updatePVs() to inform ca clients with a

DBE_ALARM event update. Otherwise this update event will be delayed

until the next driver.updatePVs() call. And in PCASpy 0.6+, every caput

triggers a call to driver.updatePVs(). That explains seeing all four

updates together, in which channel A gives a value update and B,C,D give

an alarm update.

To conclude, it is an incompatible change introduced in PCASpy 0.6. I

created an issue to track this.

https://github.com/paulscherrerinstitute/pcaspy/issues/48

In any case, it is best to explicitly call driver.updatePVs() after

calling setParam, setParamStatus, setParamEnums, setParamInfo. I will

add this the docs.

Best
Xiaoqiang

On 11/19/2017 03:47 AM, Jameson Graef Rollins wrote:

On Fri, Nov 03 2017, Wang Xiaoqiang <[email protected]> wrote:

Here is my test on linux-x86_64 arch, using pcaspy 0.7.0 anaconda
package from https://anaconda.org/paulscherrerinstitute/pcaspy

It does not reproduce the problem. Any chance that you could test using
the same setup?

Hi, Xiaoqiang.  Thanks for confirming for me.  I finally figured out
what the issue was.  In my test pcaspy IOC, on init I am attempting to
clear the "UDF INVALID" flags with the following:

     for k in pvdb:
         driver.setParamStatus(k, pcaspy.Severity.NO_ALARM, pcaspy.Severity.NO_ALARM)

In earlier pcaspy versions this was sufficient to clear the flags
without causing any additional odd behavior.  I see now that with 0.6
and later the issue I need to additionally call updatePVs() after the
above:

     driver.updatePVs()

Is this the right thing to do?  Is there a cleaner way to clear the
initial "UDF INVALID" flags?  And why is the "UDF INVALID" set
initially anyway?

Thanks so much for the help.

jamie.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System