Experimental Physics and
Industrial Control System

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.

scanOnce: Active: DEV1:trgOn

scanOnce: Process: DEV1:trgOn

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

-- 
Complexity comes for free, Simplicity you have to work for.