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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