Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Tue, 4 Jan 2011 14:36:20 -0600

Hi John,

On Tuesday 04 January 2011 13:46:19 John Dobbins wrote:
>
> I have a record connected to hardware through device support that I have
> written. I have a situation in which the record ends up in the state STAT =
> SCAN, SEVR = INVALID
>
> I looked in dbAccess.c and it appears to me that this can mean that
> MAX_LOCK requests were made to process an already processing record. Is
> this correct?

Yup, if PACT is true for MAX_LOCK successive attempts to process the record it 
will go into this state (but that won't stop the device support from running 
the second half of record processing if it eventually tries that).

> I am guessing my device support is not finishing properly so that
> consecutive requests pile up. Is this a good guess?

Most likely.  The requests don't actually pile up though, they just get 
counted, up to MAX_LOCK times, and immediately discarded.

> Apologies for the open ended nature of this query. Searching for "STAT" 
> and "SCAN" can find a lot of not particularly helpful info.

Apologies that this was not better documented, I've added a bug against the 
AppDevGuide which should at least have an index entry; SCAN_ALARM is mentioned 
briefly in section 5.9.

- Andrew
-- 
If a man is offered a fact which goes against his instincts, he will
scrutinize it closely, and unless the evidence is overwhelming, he will
refuse to believe it.  If, on the other hand, he is offered something
which affords a reason for acting in accordance to his instincts, he
will accept it even on the slightest evidence.  -- Bertrand Russell

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System