Re: [foxboro] Foxboro and Allen Bradley
- From: Corey R Clingo <clingoc@xxxxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Wed, 2 Jan 2002 16:06:39 -0600
Rob,
We have 3 Int30s addressing a number of PLCs, mostly 5/15s over DH+. We use
1785-KE modules to convert from DH+ to RS-232 (this is the "CAM"). They work
OK, except for two things:
1. We have a problem on one of them where we are unable to change the phasing
for a compound or block from phase 0; doing so causes that compound to smurf. I
send my saveall for this one to TAC, but they were unable to reproduce the
problem. I don't know of anyone else who has the problem, so it may be
something maddening with our setup. But I would not have needed to do this if
it weren't for....
2. low throughput. When I inherited the system, I noticed that our IO scan on
the station blocks on all 3 integrators was >100%. I really cannot figure out
why this is happening; in all cases, the amount of data being scanned is well
under the maximum bandwidth of the serial link. The PLCs aren't overrunning
either. When I get time I want to investigate this further
I reduced the scan frequency on many of the blocks and got the IO scan down
below 100 on two of the integrators, but the third is still close to 200%. I
was trying to move the phasing around to balance the polling (1 sec BPC, 2 sec
or greater block processing in most cases) when I discovered problem 1.
I inherited this system, and am still learning I/A, so I was not aware of the 8
PLC/16 ABSCAN block recommended limits. I know we exceed these on at least one
of the integrators, but these seem awfully low to me. Really, how much extra
horsepower does it take to drive a serial link?
Corey Clingo
Sr. Engineer
BASF Corp
Robert Driscoll <rdrisco@xxxxxxxxxxx> on 12/28/2001 08:55:06 AM
Please respond to foxboro@xxxxxxxxxxxxx
To: foxboro
cc:
Subject: [foxboro] Foxboro and Allen Bradley
Hello List,
I am installing several Allen Bradley PLCs and I want to connect them to a
Foxboro system. I know a few things about the Foxboro hardware but I have a
few questions.
How many PLCs can a single AB30 module be directly connected to? The module
has four ports, so I assume it can go to four different PLCs?
I read the Foxboro on-line document and it discussed the RS232 direct
connection to a PLC, or a connection through a CAM. My PLCs will be
networked together through a hub. Is there a Foxboro way of communicating
to the PLCs via ETHERNET? I could not find that in the
documentation. Is it possible to connect the Fox module(s) into the hub and
have the devices talk that way?
Any other pitfalls with the AB30 (or other modules that may apply here)?
Bob Driscoll
Bravo Northwest Power Systems
_________________________________________________________________
Join the world
-- No attachments (even text) are allowed --
-- Type: text/plain
___________________________________________________________________
This list is neither sponsored nor endorsed by The Foxboro Company.
Use the information obtained here at your own risk. For disclaimer,
see http://www.thecassandraproject.org/disclaimer.html#maillist
list info: //www.freelists.org/list/foxboro
subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave
Other related posts:
