PLC5/25 to Ethernet

[bluenoser337]

I have an old system with a 5/25 and lots of empty slots in the chassis. The CPU has no channel 0 port. I want to get this CPU on Ethernet for the rare occasions where I may need to troubleshoot (it would become part of another system with a PLC5 and SLC5/05). I have a 1761-NET-ENI. My question is...can I accomplish this by adding a 1771-KE in the chassis and connecting that way with the ENI? It looks like the RS-232 port on the KE is 15-pin, so I'll have to find a pinout to make a cable. Thanks! RB

 

[Operaghost]

I wouldn't add the KE module. Don't add more old outdated hardware to an already old and outdated system.

I would add a ControlLogix chassis with a 1756-DHRIO (DH+) module and a 1756-ENBT (or EN2T). Add a power supply to it and you can bridge DH+ and EtherNet/IP. Your computer on Ethernet can use that bridge to browse the DH+ network where your 5/25 is located. If you have any other devices on that DH+ you can access them too. And they can all communicate with each other across that bridge.

That also leaves the door open in the future to buy a ControlLogix CPU to replace the 5/25.

OG

 

[bluenoser337]

Thanks for the reply operaghost but the purpose is to do this as cleanly as possible using the older parts, which were great in their day...and still can be. Also, the DH+ isn't used on the 5/25. It is set up as a RIO scanner.

 

[Ken Roach]

The 1761-NET-ENI's serial port is hard-set for DF1 Full Duplex point-to-point, and is only meant to be connected directly to a controller's serial port that is also set up for Full Duplex point-to-point.

The Net-ENI considers itself Node 0, and considers the PLC to be Node 1.

So you can't connect a Net-ENI to a 1770-KF2 or 1771-KE or 1785-KE and "browse" or connect to a multipoint network like DH+, because the only possible target address is DH+ node 1.

You could still use it in a system like you describe, though, where the PLC-5 and the 1771-KE are the only nodes on the network. The PLC-5 would be Node 1 and the 1771-KE could be any node number other than 0 or 1 (it's functionally transparent).

The "Classic" PLC-5 models like the PLC-5/25 don't have a Channel 0 serial port. That 15-pin port is actually a DH+ port, and is wired internally to the 3-pin Combincon connector below it. The top two connectors are DH+ only, and the bottom one is RIO only. They can't be configured for either protocol like the Enhanced/Ethernet/ControlNet PLC-5 controllers can.

You will have to carefully research and build cables to go from a 1761-NET-ENI Mini-DIN8 serial port to the 15-pin RS-232 port on the 1771-KE, and another from the 15-pin Data Highway port on the 1771-KE to the 15-pin (or 3-pin) DH+ port on the PLC-5/25.

A 1756 chassis with a ENBT and DHRIO would still be my go-to devices, especially because it could later host a 1756 CPU.

The ENI + KE would add some latency to every packet, but it should still work.

 

[Ken Roach]

Full disclosure: I don't know for sure if the Data Highway port on the 1771-KE and the Data Highway Plus port on the PLC-5/25 are completely compatible.

I *think* that for these purposes DH+ is basically DH with some more function commands and higher speeds. But I have worked on so few DH systems I don't know.

The 1785-KE is the version of the slot-mounted DF1 to DH+ gateway that was DH+ from the beginning.

 

[bluenoser337]

Thanks Ken!! for all the details. I have the hardware so I just need to figure out my cables and then I can give it a try.