Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Wed, 09 Dec 2009 16:06:23 -0500

Hi,

I agree with Dirk's statement.

I would like to add, though, that currently if the D.INP link is A.CP

(or D is passive and D.INP is A.CPP), D *will* get processed when the CA

link is set up, independent from its PINI value. Reason: .CP and .CPP

input links are implemented as CA monitors, and will get a value when

the connection comes up. At that point, that first incoming value update

is not distinguished from later updates, and the record is processed.

Again: I agree with Dirk that D should probably just be initialized, not

processed on reboot of ioc2.

But I'm not sure if that can be implemented easily (records may have

many .CP inputs, so checking UDF is not sufficient), and I want to point

out this would introduce a serious change in behavior, that could

possibly break many existing databases.

I can see the unexpected string type link behavior possibly being

intended to do something like an auto-save/restore on record C. This

could be an interesting feature, if (and only if) it is independent from

data type (obviously) and configurable (which requires a CA protocol

change to allow the link spec to define target record processing -

instead of the PP option of the target field now used for that purpose).

Cheers,
Ralph

On Wed 09 Dec 2009 4:58:26 Dirk Zimoch wrote:

Hi Andrew,

My personal opinion is that a record which is not processed should not

"do" anything. That means it should not cause other records to process

and should not change their value. I think the original idea behind

processing a record is that this is the only time where a record is

"active". Maybe apart from the time when it initializes. But even then

it should not process other records.

Let's assume this situation:
ioc1:
A
B.OUT-> C

ioc2:
C
D.INP -> A

I think the "correct" behavior is:

When ioc2 reboots, C becomes INVALID/UDF and only gets a copy of B

when B processes. D gets initialized with a copy of A. Neither C nor D

gets processed unless they have PINI set.

Dirk

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System