DH+ Interface modules on a PLC5 Chassis

Hi

I was wondering if it is feasible to have more than one DH+ interface cards in one single PLC5 chassis, in order to partition a DH+ network into several drops. Each drop will connect to a set of SLC504.

Is it possible? will the chassis and processor take it?

Thanks !

sherman4 said:

DH+ interface cards

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What card would you be talking about?

Why would you want to do that? Why not just daisy-chain everything on the DH+. Here's a link to the A-B DH+ Installation Manual

If you're talking about using a 1785-L40 or bigger that will let you run up to four DH+ channels, then yes. A network of DH+ nodes while allowing up to 64 node addresses on a network, becomes slower and slower when more than 7 nodes are connected. You can segment your network into two halves if the SLC's don't have to talk to each other thru the PLC-5 as you won't be able to route messages across the PLC-5.

SLCs networking

Thank you all for your replies...

I am interested in networking a total of 70 SLCs, they will not exchange any data within themselves, just pass data up to a master higher processor. If DH+ (partitioned or not) is not an option.... can anyone suggest a cleaner, cheaper solution???....

Thanks !!!!

The SLC's seem to be better at getting along on a DH+ network than the PLC-5's. You can't have 70 SLC's and a PLC-5 on a single network segment anyhow. The maximum number of addresses on a single DH+ network is 64. If you havn't purchased the PLC-5 hardware yet I would recommend taking a look at the ControlLogix platform for the data concentrator. You could split the SLC504's up onto 4 different DH+ segments plus have an Ethernet module to access the data via a higher network. I added up the cost of the hardware and the ControlLogix came out under the cost for the same thing with PLC-5.

What if I use DH485 ???

Hi PLC Doctor !!

That sounds like a fine idea, using a ControlLogix platform as the master will provide higher connectivity... but I wonder if I can still implement this solution using SLC5/03 controllers through many DH485 segments. Is there a DH485 interface card for ControlLogix that would enable me to have several DH485 links on the same ControlLogix?

Thanks again! your ideas are greatly appreciated.

sherman4,

PLCDoc brings up a good solution for you. New Control Logix processors support DH-485 on their RS232 ports now, so that can be an option. Their will also be, if not currently available, a 1756-DH485 module that will have (2) DH-485 ports and will be configurable much like the other comms. modules. Give your AB guy a call.