Re: [foxboro] FBM231 modbus with siemens
- From: Corey R Clingo <corey.clingo@xxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Mon, 22 Oct 2007 17:26:55 -0500
Is there a block configured to read address 40001 in this application?
If not, this certainly sounds like an overreaction on the part of the
Siemens PLC, but the FBM231 is not completely blameless; it should not be
polling for unconfigured data.
Corey Clingo
BASF Corporation
"Wilson, Brad" <brad.wilson@xxxxxxxxxxxxxxxx>
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10/19/2007 09:03 AM
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Re: [foxboro] FBM231 modbus with siemens
In trying to set up a FBM231 with a Siemens S7, I discovered that the
FBM231 tries to establish a comm link with the PLC before sending a
request. In the absence of a heartbeat, it sends a read request to
address 40001 (the first entry of the holding register. If the Siemsns
receives a request to an undefined address, it shuts down the comm port.
So, if 40001 is undefined then the PLC immediately goes off-line and can
only be restored by cycling power. There may be other "odd" behaviour
associated with Siemens too. Be sure that heartbeat (FC8) is turned on.
It would seem that standard modbus is not always so "standard".
Brad Wilson
brad.wilson@xxxxxxxxxxxxxxxx
Invensys Systems, Inc
1090 King Georges Post Rd, Suite 204
Edison, NJ 08837
732-874-0087
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