What In The World Is A Single Protocol Gateway

One of the really great things about having a good communication channel with customers is that they can tell you the kinds of products they need.

A few weeks ago, a customer came to us with an interesting problem. They have two Allen-Bradley PLCs in different parts of the factory and they need them to communicate. They are not currently connected by a router.

In this particular organization, getting involved with IT and an IT Router is not an attractive option. The control engineers don’t mesh well with IT, and stuff like this causes delays, headaches and fights over message priority. IT wants assurances that the control network won’t flood its network with unwanted messages and it has (legitimate) security and other concerns.

To solve this problem, the control engineer could buy a router, configure it, install it and support it, but that would still cause headaches when IT discovers it. A router isn’t really an attractive option.

When talking to the control engineer, one of our application engineers figured out that we could solve this problem simply, easily and cheaply with a single protocol gateway. “What’s a single protocol gateway?” you might ask.

Well, as the name implies, it’s a gateway that only supports a single communication protocol. And the key factor in this solution is that it has two network interfaces (NICs). Two NICs means that it can operate on two subnetworks at the same time, as in the previous diagram.

This unit does EtherNet/IP CIP reads and writes on subnet 1 using an IP address on subnet 1. It also does EtherNet/IP CIP reads and writes on subnet 2 using an IP address on subnet 2. The tags from each plc are cross-mapped from one PLC to the other.

In this case, the application is using 460ETC one-protocol gateways, but we have the same thing for Modbus TCP, Siemens S7 PLC gateways and any number of other products.

For more details, contact one of our application engineers at sales@rtautomation.com or call 262-436-9299.