In article <c4aa35eb.0311061930.1262a64c@posting.google.com >, razorbak71
@yahoo.com says...
> First, I know nothing about PLC's, but I was wondering is there a way
> to extract data from a SQL database file, feed that to a PLC is some
> manner, and then have the PLC trigger a diverter gate based on the
> value in the table exceeding a certain value, to divert parts to
> another location.
>
> Am I off base, or is there something out there that will allow or help
> me to do this. Any help would be greatly appreciated.

This is done all the time in control systems - been doing it for almost
10 years myself.

There are many ways to do this, but it depends on which PLC you are
using.

Most common methods are a VB app speaking DDE to a PLC communications
app that lets you specify a address/data type.

Other methods include HMT/MMI screen applications that already have the
ability to interface with the database and PLC and act as the middle
(communications) path.

There are also things like RSSQL by AB/Rockwell that make this real
nice.

Keep in mind one thing - do not write the set-points directly to the
registers used to control the gate. Put the set-points in a holding
area, check them for valid range, then move them to the set-point area.

My email address is shown below (remove the 999) if you want to email me
about this.

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