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SLC 504 to Ethernet
Is there a card that will allow a SLC 504 to communicate via Ethernet?
By Hassan Ajami on 12 February, 2004 - 12:51 am

We have an DCS system that can communicate with PLCs via ethernet links.

The PLCs installed are SLC 504s which communicate via DH+ but not ethernet. Is there any card/module that will allow communication with the SLCs via ethernet?

By Tomas Fever on 12 February, 2004 - 7:14 pm

A-B's 1761-NET-ENI

By Gerry Morris on 12 February, 2004 - 10:01 pm

Part number 1761-net-eni, if the SLC's RS232 port is available. This hardware mounts outside the chassis. See the manual at:

Gerry Morris
NEDDAM Software Technologies

By Pedro Miguel on 12 February, 2004 - 10:56 pm

I Have the same trouble but Ehernet have many protocols, there are expensive cards in the market, the other option is use the SLC505 with a port Ethernet built-in, but the protocol is AB Protocol.

My solution is to use the Serial port in order to use a programmable gateway to AB Ethernet that solution takes time but is very inexpensive (hundred dollars) compared to expensive cards (Thousand dollars).

With the experience in programming the serial/ethernet gateway devices you could integrate any device in your plant with the minimum cost.


Pedro Miguel

By Gerald Beaudoin on 12 February, 2004 - 11:09 pm

There is an ENI module that you can hang on a SLC to enable EtherNet capabilities. Check with the AB rep... they can send you the blurb sheet on it or check out the Rockwell website.

Gerald Beaudoin

By Danny Jameson on 12 February, 2004 - 11:16 pm


Ruggedcom makes a product that has either 4 - RS232 or RS485 ports, as well as a fully capable ethernet switch built in. You can even optionally have a modem built in for redundant back-up communications. This unit would allow you to connect up to 4 PLCs to Ethernet. For more information... visit...

Try either Allen-Bradley's NET-ENI Module

or Digi's One IA RealPort

Either one will convert DF-1 protocol to EthernetIP. I only have personal experience with the NET-ENI.

By Alan Hartwell on 13 February, 2004 - 1:05 am

You didn't specify what Ethernet protocol you required. ProSoft Technology ( makes a couple of in-rack modules for the SLC. The MVI46-DFNT handles EtherNet/IP Client/Server communications. The MVI46-MNET handles Modbus TCP/IP communications.

In addition you might look into Allen-Bradley's 1761-NET-ENI ethernet interface. It bridges ethernet to the serial port of the SLC processor.

If the serial port is open, the 1761-NET-ENI will meet your needs. It is an Ethernet to DF1 conversion.


By Ian Phillips on 13 February, 2004 - 1:20 pm

You can use the 1761-NET-ENI module. It connects any DF1 device (SLC 5/04 channel #1) to AB Ethernet.

Ian Phillips
flomation engineering

Go to Prolinx gateways. They have a module and a stand-alone device. I suggest the stand-alone device. Use DF1 or DH+.

By Lynn at Alist on 13 February, 2004 - 2:05 pm

Our DigiOneIA-RP can easiy map the older CSP protocol to DF1 for the the SLC5/04's serial port/channel 0. Most vendors call this AB/Ethernet (which doesn't really exist). We also support COM port redirection.

So in RSLinx you'd either select:
1) DF1 Serial Devices to the Digi's virtual comm port
2) or 'Ethernet Devices' (not 'Ethernet/IP Devices')

In either case, the icon for your SLC should show up along with the IP address in the Digi. Web page is here:

Just keep in mind that RSLogix saves the "driver" within the PLC program, so if you downloaded your program last by RSLinx direct to the computer's COM1 with DF1, then the FIRST thing you must do after accessing the Digi+SLC5/04 is to do an upload and save. This changes the comm path to AB_ETH-Local (or whatever you called it).

Of course, there is also Rockwell's ENI module you can find at It uses PCCC encapsulated in Ethernet/IP, and cannot appear as a virtual COM port.

By the way, CompactLogix users, RSLinx will happily use the virtual COM port function to access a DigiOneIA-RP direct by Ethernet to a Compact or ControlLogix DF1 port. ENI series A cannot do this.

best regards
- LynnL,

You can also use Prosoft's in rack module if all you want to do is send data from the SLC5/04 via ethernet. You cannot program over it but it will let you access the SLC data tables.

By Bob Peterson on 13 February, 2004 - 9:36 pm

Call your local AB distributor. there are several ways to do this, but you have to make sure it is compatable with your host computer. easiest solution is to just replace them with 5/05s, and if there is just 1 or 2, that might end up being cheapest.

you can also get a contrologix chassis with an ethernet card and a dh+ card in it that will allow communications, however as far as I know, this requires RSLinx on the other end, something that your host may not have.

Bob Peterson

By Bob Peterson on 22 February, 2004 - 4:13 pm

I should have provided more details in the first post.

The ethernet protocol should be the older CSP (AB Protocol). The Prosoft card only does the newer EIP so it won't work, I'm not sure what the AB 1761 card does.

We can't switch to 505s since the 504s are already there and programmed (18 of them). Would be too expensive to swap all of them out. Maybe your best bet si to buy a contrologix xhassis, but an enet and a dhrio card in it. that way you can bridge from the ethernet line to the dh+ line, assumming your host supports such a configuration. otherwise you may need to add a 5/05 and rack to the mix and use the 5/05, enet, and dhrio card to collect data from the other plcs and let the host talk just to the 5/05.

a lot depends on just what your host computer supports. some dcs systems do not support more complex arrangements.

Bob Peterson

By Steve Tilman on 16 February, 2004 - 8:53 am

I know that AB offers their NET_ENI module which we connect to the DF1 port of the 504 for use with an OPC server from kepware. If Kepware is doing it on ethernet I'm sure you should be able to do it if the techical information is available.

By Hassan Ajami on 19 February, 2004 - 11:58 pm

Thanks for all the replies.

I should have provided more details in the first post.

The ethernet protocol should be the older CSP (AB Protocol). The Prosoft card only does the newer EIP so it won't work, I'm not sure what the AB 1761 card does.

We can't switch to 505s since the 504s are already there and programmed (18 of them). Would be too expensive to swap all of them out.

By Lynn at Alist on 22 February, 2004 - 12:12 pm

The DigiOneIA-RealPort happily maps CSP (ie: older Ethernet on TCP port 2222) to DF1. It also supports newer EIP, but to be honest the older CSP is more efficent for simple PCCC style comms. It is an external serial/Enet module - but your message sounds like you are expecting a SLC rack module.

What Master/Client software are you running that you are limited to the older CSP protocol? Or do you have older SLC5/05 & PLC5E that haven't had firmware updates?

best regards - LynnL, Snr Prin Engineer for email address see:

By Julian Ward on 24 March, 2004 - 6:04 pm

Take a look at it is a DH+ to EtherNet convertor.