AB PLC 5/40 Ethernet connection

At work we need to connect one of PLC 5/40 to ethernet, I would like to do this without changing over the processor to a 5/40E, or the use of a sidecar, adaptor module etc.

So my question is, can you use the 25 pin serial port on a PLC 5/40 for ethernet connection, using a 25 pin to RJ45 adaptor and get it to communicate? If so, how.

The 25-pin port on the PLC-5/40 controller is an RS-232 serial port.

This is fundamentally different from the similar-looking 15-pin AUI port that was used for early Ethernet connections, including those on the PLC-5/40E.

An AUI port may be connected to Ethernet using an AUI-based media converter. While these are functionally obsolete, some specialty vendors continue to produce them and surplus units are widely available on the aftermarket.

To connect an ordinary PLC-5/40 serial port to an Ethernet network, you would need an RS-232 to Ethernet converter like the Allen-Bradley 1761-NET-ENI or the Digi One IAP.

I have costed the 1761-net-eni, its about $750 through westburne, if there was a cheaper way we were going to start switching more of the plc 5's over from dh+/rio to etherent.

Serial interfaces are always bottlenecks; you will very likely not see improved data throughput using a Net-ENI or Digi One IAP, as compared with DH+.

Only you can determine if the flexibility of having Ethernet access to your controller is worth the cost of the interface.

OK, Finally found an older PLC5/40E with the old 15 pin ethernet port, how do you convert to an RJ45 to use Cat5e cable from the 15 pin?

As noted above, that's called an AUI Interface.

The CentreCom 210T was very popular, back in the day. You can pick one up on eBay for twenty bucks.

perfect I think we still have a couple of those around from some old hermary scanners. I assume once I locate the centercom its just folllowing the manual to setup a driver and ip address.

I found the Center Com 15pin to RJ 45 converter this morning, used a KT-1 DH+ connection to the 5/40E to start the setup on the channel 2 in channel config, I have the ethernet address of BC:1C:2A:2D, which I believe converts to 188.28.42.45, which I entered into the IP address what do you enter into the subnet?

typically its 255.255.255.0 or 1 but I read on another fourm not to use 255. After that the Laptop IP of 192.168.1.1 will go into the gateway address, is that correct?

The address you're seeing in hex is the hardware MAC ID of the Ethernet port on the PLC-5/40. I recognize it because it's characteristic of Allen-Bradley hardware.

That's the hardware layer underneath IP, so you need to configure an IP address of your choice.

If you are on a typical office subnet with a gateway IP address of 192.168.1.1, then your PC and your PLC can have a final octet that is unique to them.

Typical addresses would be "192.168.1.3" for the PLC and "192.168.1.10" for the computer. The last value is the "last octet" and is what differentiates devices on this sort of network, which has a Subnet Mask of 255.255.255.0 and is called a "Class C Private Subnet".

This is very basic, low-level IP addressing stuff. If you're unfamiliar with how IP addresses work, you should get some help or read up on one of the zillions of tutorials on the Internet. You could cause some confusion or downtime if you just go plugging numbers into devices and connecting them to your automation or enterprise networks.

Thanks Eddie, for the info, got this to work, using the channel 2 on the 5/40e. For one reason or another I thought I had to convert the MAC address because in the manual it says to phone Allen Bradley for the I.P address. That turned out to be a misleading or I read it wrong. thanks again.