Experimental Physics and
Industrial Control System

Michael Davidsaver via Core-talk <[email protected]> · Mon, 26 Aug 2019 10:42:15 -0700

This might be https://bugs.launchpad.net/epics-base/+bug/1745039

Any chance you can try to reproduce with Base 7.0.3?

> (2) if a record (here: DEV1:trgOn) is active (PACT=1) when an event
>     arrives, it gets processed again, after completing.

This was only true when a record was processed directly by dbPutField()
(eg. via channel access).  "CPP" links use dbProcess(), which didn't do
this.

On 8/26/19 9:46 AM, Benjamin Franksen via Core-talk wrote:
> I am using base-3.15.6. This is a part of a larger database, running on
> a soft IOC on Linux:
> 
> record(calc,"DEV1:st") {
>     # the field details are irrelevant here,
>     # just note this is a simple soft record
>     # that gets processed via CPP input links
>     field(INPA,"DEV1:stZ CPP")
>     field(INPB,"DEV1:stS CPP")
>     field(CALC,"A<<4|B&0xf")
> }
> record(calcout,"DEV1:trgOn") {
>     field(INPA,"DEV1:sel")
>     # trigger processing on change of readback
>     field(INPB,"DEV1:st CPP")
>     field(CALC,"A==B")
>     field(DOPT,"Transition to non-zero")
>     field(DTYP,"Async Soft Channel")
>     field(OUT,"DEV2:switch CA")
> }
> 
> The values involved are all integers.
> 
> DEV1:sel is the setpoint, DEV1:st is the (soft) readback, which gets
> triggered by writing DEV1.sel via a chain of FLNKs, OUT PP links and CPP
> input links. The idea is to write a "1" to the DEV2:switch (which is a
> different device controlled by another IOC) when the readback has
> settled to the same value as the setpoint. The device DEV1 is complex
> and requires various separate commands to effect the change, and the
> readback can go through 2 or 3 different values before finally
> coinciding with the setpoint.
> 
> When I set DEV1:sel (using caput) to different values, I can sometimes
> get into a situation where the database has the following (persistent)
> state:
> 
> DEV1:sel.VAL=0
> DEV1:st.VAL=0
> DEV1:trgOn.A=0
> DEV1:trgOn.B=8
> DEV1:trgOn.VAL=0
> 
> I think this should not be possible, assuming that
> 
> (1) the value of the last monitor event (here: from DEV1:st) always wins
>     over previous events, and
> 
> (2) if a record (here: DEV1:trgOn) is active (PACT=1) when an event
>     arrives, it gets processed again, after completing.
> 
> Either this is a bug or at least one of my assumptions is wrong. I
> wonder which.
> 
> Cheers
> Ben
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System