1761-NET ENI wont see PLC5s

Hopefully, one of you will have an answer to a dilemma I'm having.

I have a SLC5/04 that is currently using DH+ to transmit equipment status info to various PLC5s throughout the mill. I am trying to eliminate all of our DH+ communication and convert to Ethernet. It has a 1761-NET-ENI connected to channel 0 for Ethernet communications. Of the five PLC5s I am trying to message to, only two will successfully connect. I did notice that in looking at RSlinx the PLCs that can be messaged to are visible when using the Ethernet/IP device driver, but not the other three. When using the Ethernet devices driver Rslinx sees all five of the PLCs. I have messaging between the PLC5s with no problem.

1. Could the reason for the problem be due to the PLC5s not being of a new enough series and/or revision?

2. Would an upgrade to a SLC5/05(has integral Enet port)allow me to message with the older PLC5s?

This isn't a critical problem, and we are trying to stay as inexpensive as possible if we need an upgrade. Changing to micrologix or compactlogix would be too involved an expensive for what we need to do, we have a source for a relatively cheap SLC5/05.

Thanks
Mark Snodgrass

The short answer is: "Yes, and yes".

The 1761-NET-ENI only supports the modern "EtherNet/IP" messaging protocol used by ControlLogix and MicroLogix.

PLC-5 and SLC-5/05 controllers originally used an A-B proprietary protocol called "CSPv4" on Ethernet. Both the PLC-5E and SLC-5/05 were upgraded to support both protocols in the late 1990s. There's a technote on the RA Knowledgebase showing the specific firmware revisions for each Series of PLC-5, but the RSLinx driver difference you pointed out is also a deductive way to figure out which protocols the PLC-5 supports. Only a device that supports the modern EtherNet/IP protocol will respond to the broadcast "List Identity" command that the EtherNet/IP driver uses to browse the network.

Another cool trick is to use the TCPing utility to check whether the TCP Port 2222 (CSPv4) or 44818 (EtherNet/IP) is open on the controller.

You're also on the ragged edge of the number of outgoing connections a 1761-NET-ENI will support; my recollection is that it will support a total of six outgoing TCP connections.

If you do get an SLC-5/05 to perform this function, check its firmware revision to be sure that it supports both CSPv4 and EtherNet/IP.

Thanks Ken, that's kinda what I was thinking it might have been. I just needed someone to confirm it. My source for the new SLC5/05 is a crack programmer and im sure he will be able to get me the right version.

Thanks
Mark Snodgrass