Re: [foxboro] ABSCAN Detail Display information

I want to say that the answer is yes, but having never used event-driven
comms, I can't say for certain. Since ABSCAN is acting as a slave to the
PLC controller, how would the PLC normally know to "request" that the
ABSCAN write any outputs to the PLC? Unless the controller is also
monitoring the ABSCAN for changes compared to the controller's data
table. But B0193RG doesn't state explicitly (or even imply, imho) that
is the case.

Brad Wilson
brad.wilson@xxxxxxxxxxxxxxxx
Invensys Process Systems, Inc
1090 King Georges Post Rd, Suite 204
Edison, NJ  08837
732-661-4012 o
732-874-0087 c

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Tim Ruhland
Sent: Thursday, June 11, 2009 2:30 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] ABSCAN Detail Display information

Thank you for confirming that documentation on the UPDATE parameter of
an
ABSCAN block is non-existent. I was beginning to think I was having a
prolonged senior moment or even another breakdown (lost count, long ago)
;)
Some follow-up questions (may be just one question worded differently):
Given SCNTYP=1, and an output block connected to a particular address
and in
AUTO - then setting the UPDATE parameter on the ABSCAN block causes the
ABSCAN block to read the data from the PLC? So...if the data is
different
than the values on the output block, the output block values will then
be
written to the PLC?

So setting the UPDATE parameter on the ABSCAN block will "update" any
input
block values to match the values in the PLC and "update" the PLC data
table
to match any output block (in AUTO) values?

Regards,
Tim Ruhland


On Thu, Jun 11, 2009 at 6:30 AM, Wilson, Brad
<brad.wilson@xxxxxxxxxxxxxxxx>wrote:

> You undoubtedly saw that the visible of the UPDATE button is connected
> to SCNTYP. When ABSCAN is in event-driven mode (SCNTYP=1) the UPDATE
> button is visible and selecting it sets UPDATE to 1, thereby forcing
an
> ABSCAN update as if an event had triggered it. UPDATE should then
reset
> back to 0 to await the next trigger, either by an event or by the
UPDATE
> button. Normally the A-B controller monitors its data table and sends
a
> trigger if it sees any change. Although I haven't tried it, you should
> be able to set UPDATE from any script and accomplish the same result.
>
> When SCNTYP=0, the ABSCAN is in polled mode and doesn't wait for a
> trigger from the controller, but rather sends read messages on a
regular
> basis. The UPDATE button is invisible.
>
> You're correct that the UPDATE button is not documented well (at all)
in
> B0193RG, which is very detailed in describing the SCNTYP variations,
and
> the operation of UPDATE should derive naturally from that.
>
> Brad Wilson
> brad.wilson@xxxxxxxxxxxxxxxx
> Invensys Process Systems, Inc
> 1090 King Georges Post Rd, Suite 204
> Edison, NJ  08837
> 732-661-4012 o
> 732-874-0087 c
>


 
 
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