Re: [foxboro] Foxboro and Allen Bradley

 --- Robert Driscoll <rdrisco@xxxxxxxxxxx> wrote: > 
> 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 believe you will be able to direct connect to two PLCs, or
alternatively to two DH+ networks, addressing as many as 8 PLCs,
although I've only ever configured the ports as redundant (rather than
multi-path). Direct connect is limited to PLC-5/40 or PLC-5/60 or
SLC-5/04.

> 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?

Micro I/A modules can talk Ethernet to PLC5s, but each module can only
address one PLC.

The most common method of communication between an Integrator 30 module
and several A-B PLCs that I have used is to connect the PLCs with a DH+
network and use the AB30 via a CAM on the DH+ network.

> Any other pitfalls with the AB30 (or other modules that may apply
> here)?

Communication can be relatively slow (compared to the ethernet between
PLCs) between the AB30 and the PLC(s) because of the speed of the
serial link.

One other module to consider is the A-B Station.  This slots in next to
the processor on a PLC5, and is on the I/A nodebus via a DNBI or DNBX. 
I have found configuration to be more straight forward (ie. more like a
CP) than with an AB30.  Data throughput is fast, because there is the
A-B Station has direct memory access of the PLCs data tables. 
Communication with multiple PLCs through one A-B Station can be managed
by setting up data tables that echo the state of those on another PLC.

Regards,

Kevin FitzGerrell
Foxboro New Zealand
+64 9 573 7690
> 
> Bob Driscoll
> Bravo Northwest Power Systems
> 
> 
> 
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