PLC5 and Ethernet


Thread Starter


We have a large warehousing application running on a 5/80, which we really don't want to have to change. Can anyone think of an easy (and not too expensive) way to read/write its data table from a PC over ethernet?

I've considered just sitting an SLC5/05 next to it, but that seems a bit of a fudge.
What is the type of device that wants to communicate with the 5/80, PLC, PC, etc.?

Jason Valenzuela

Bob Peterson

You can use the serial port on the 5/80 and read it using the DF1 protocal. It's slow, but if you don't need much data it will work.
The most functional way to do it is to get a 1785-ENET "sidecar" interface that goes in the adjacent slot. Since you're running a large application you're probably going to want the best data throughput you can get. The new Series F 1785-ENET modules have a 10/100Base-T port right on the front and don't require a transceiver like the old ones did.

If you have the Channel 0 serial port on the PLC-5/80 available, you can use a 1761-NET-ENI to connect to RSLinx or other A-B controllers, or use a Lantronix/Moxa/Digi RS232/Ethernet terminal server to allow a PC (like the RSLinx DF1 driver) to access the controller. This will be much slower but half as expensive as the sidecar.

Your other options involve bridging to the existing DH+ network, especially if you have ControlLogix system in the facility as well. You'd have to post more about your architecture to solicit recommendations on that.

Jeremy Pollard

Digi International offers a device server that can support 2 sessions (one for HMI and one for RSLOgix) as well as Lantronix.

Inexpensive and they work... I have experience with Digi... the driver on the computer uses a virtual com port which is supplied.

Very cool, and very practical.

Cheers from: Jeremy Pollard, CET The Caring Canuckian!

Michael Batchelor

Go to eBay, buy a dirtball cheap PLC-5/20E, 1771 4 slot rack and power supply. Then set up the same game plan you were thinking about for the SLC5/05, but for about 20% of the cost. Yea, it's a kludge. But it will work, and it's cheap.

Now, would I sell you that solution if you were expecting me to warranty it? Not on your life. The only way I can stay in business is to provide
solutions that don't have me coming back under warranty to fix the workarounds. However, if you are not going to spend the money to buy a 5/80E, then you you're obviously going to do it yourself. And this *WILL* work. The only oddball part of it is that the PLC5 Ethernet connectors are an AUI port. If you don't have gray hair you might not
have ever seen one of those. You'll need an adapter for it.

Michael R. Batchelor

Industrial Informatics, Inc.
3281 Associate Dr.
N. Charleston, SC 29418

843-329-0342 x111 Voice
843-412-2692 Cell
843-329-0343 FAX

Mike McDermott

There are several ways to do this.
1. Buy the Ethernet card from AB. Only pitfall to this is that it HAS to reside in slot 1 right next to processor.

2. Put a Net-Eni (AB) module on the serial port and then Ethernet into the Eni module.

3. If you have a DH+ or RIO network on the PLC5, you can buy a ControlLogix Backplane, add an 1756-Enbt and a 1756-DHRIO card. Then you can go from DH+/RIO to ethernet.

The latter is what I use, and it works very well.