[foxboro] Modbus Communication bus a mess when failed slave

From: Sergio Gonzalez <sgonzale16@xxxxxxxxxxxxxxxxx>
To: foxboro@xxxxxxxxxxxxx
Date: Thu, 2 Sep 2010 19:57:28 -0500

Hello everyone
I have a problem with a communication bus and I would like some help please.

This is the architecture: There is an Integrator 30B (FT) which two buses go
through a Modicom bridge/mux (BM85). In this Modicom device there are two
cables in and two out.

The input cables are the buses A and B for a RS485 (4wires) network. In
network A there are 4 slaves (old Siemens PLC S7) that use a Blackbox
RS232/485 converter (LD485A) (4 Wires), pending to be upgraded to ADAM 4520.
In network B we use ADAM 4520 RS232/485 converters (2wires).The output
cables go to the DCS (A and B bus)

On the one hand, when all slaves are ok, the whole network is well and
steady. On the other hand, when any of them fails (ECB16 Red), the network
is a mess: the A bus fails for the 4 slaves and next the B bus too. Then
some of the salves get well (ECB16 White) temporally and then fail again.
Sometimes one of them gets white steady and the others change. To avoid
losing communications we have to turn off the failed slave.

I´m checking and changing the gateway parameters and I can?t find anything
by software to handle those errors.  Any suggest? Does this look like a
grounding problem?

Thanks a lot in advance

Regards!


This is the primary block configuration and the ECB16:

NAME   = MOD007_ECB:PRIMARY_ECB

  TYPE   = ECBPG

  DESCRP 
  NRBUS  = 2

  BUSOPT = 3

  BUSTYP = 3

  PIOWDT = 3

  MPOLL  = 7

  BAUD   = 4

  DATBIT = 8

  PARITY = 2

  STPBIT = 1

END


NAME   = MOD007_ECB:PLC005

  TYPE   = ECB16

  DESCRP 
  DEV_ID = PLC005

  HWTYPE = 32

  EXTYPE = 0

  SWTYPE = 16

  PCTYPE = 4

  PCADDR = 1

  HBEAT  = 1

  MULTWR = 1

  PLCRIT = 0

  FLTPNT = 1

  RES02  = 3

 
 
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[foxboro] Modbus Communication bus a mess when failed slave

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