In the gold mill I work for we do most of our regulatory control over the
node bus with no problems. Most of our control structure runs in a CP30,
and much of our I/O is through AB-stations to PLC5s. Setting up good error
handling and initialization is more critical when all the I/O and control
is not in the same compound or CP, but our only significant problems have
been when one station needed to be down for maintenance and it controlled
critical I/O for another.
The only problems we have had in 3+ years of use on our carrier-band LAN
have been cable problems. My feeling is that we would have been just as
likely to have these problems with hard-wired lines to the field devices,
however we are currently using the CB-LAN only for operator interface
rather than control.
Although our control is fairly complex and extensive (about 6000 total
blocks in DCS, control covers wide variety of processes: crushing,
grinding, leaching, stripping, etc.) the processes I am controlling are
inherently safer than those of a typical refinery (mud is not very
reactive), and we typically can schedule DCS related maintenance during
semi-annual grinding mill liner changes, so please take my two cents worth
here with this in mind.
Kevin FitzGerrell
Fairbanks Gold Mining, Inc.
Fairbanks, Alaska
> -----Original Message-----
> From: Murphy, Daniel J [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, March 30, 2000 2:54 PM
> To: 'Foxboro DCS Mail List'
> Subject: RE: Detection of nodebus-failure
>
> I would be interested to know what the concensus is out there for doing
> regulatory control across the carrier-band LAN. For example, one PID
block
> in one node talking to an AOUT block in another node.
>
> Here we don't trust the CB-LAN to do basic regulatory control. We prefer
> to
> hardwire the signal via FBM's. Anyone else do the same?
>
> The same question applies to peer-to-peer communications within a node.
> Anyone hardwire these connections as well?
>
>
> Dan Murphy
> BP Amoco Refinery
> Brisbane Australia
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