Network Communication with Automation Controllers

| Dan Simpson

Automation Controllers

Connecting Your Automated Systems

One of the questions I get asked often relates to what network communication options are available with the myriad of automation controllers available today. The use of these communication options varies as much as the different protocols that have been created over the years. Connecting disparate controls from different manufacturers always presents its set of unique challenges. This all said, there is a subset of these protocols that I receive inquiries about time and time again. Fortunately, Rockwell Automation supports this subset natively, i.e. it is built into many of its controllers. Protocols such as Modbus RTU, Modbus TCP, DNP as well as the ever-popular Ethernet/IP are few of the more popular interfacing methods. This post will discuss the native protocols that are available in Rockwell Automation® controllers and options beyond that scope.

Native Protocol Support vs. Third-Party Modules

Automation Controllers for Network CommunicationsAutomation Control PanelsI should also mention here that although the desired protocol may not be built into the PLC product per se, there are several “third party” companies that produce hardware modules that are compatible with many of the Rockwell Automation controller I/O systems. In some cases, especially with older or legacy type equipment, a communication gateway is required. This stand-alone device translates or maps the data values from one type of communication interface, typically to a more currently used protocol. In the case of Rockwell Automation controllers, we are usually converting legacy systems to be compatible with Ethernet/IP.

  • Rockwell Automation controllers will offer native protocol support
  • Third-party options are available with in-chassis protocol modules

Research Tool: Option Comparison

To aid your research into what your communication options are for the various PLC/PAC systems available from Rockwell Automation, I have compiled a spreadsheet that provides this particular feature set. You can download it here (Excel file, approx 0.1 MB file size).

Let’s take a look at an example. You are using a MicroLogix 1400™ controller:

  1. Rockwell Automation Serial Protocols supported are: DF1 Full Duplex, DF1 Half Duplex Slave & Master, DF1 Radio, DH485, ASCII
  2. Rockwell Automation Network Protocols supported are: Ethernet/IP (Explicit Class 3 messaging only)

You can also use this spreadsheet to ask a different question: “I know what communication options are required by this system. What controller should I select?” This is the same question, a different way.

MicroLogix 1400

The Allen-Bradley® MicroLogix™ 1400 from Rockwell Automation complements the existing MicroLogix family of small programmable logic controllers.

Technical Support for YOUR Automation Controllers

As I had already mentioned, these controllers don’t all support the protocols you are looking for natively. The spreadsheet does indicate which controllers support these third-party protocols as an embedded feature. In that same sheet, I have indicated whether there is a company that can supply a plug-in module (or in-chassis style) to support these interfaces. If neither is available, then it always possible to get a gateway module to go from Ethernet/IP to one of the other popular protocols.

Do you have further questions about automation controllers, networking, and communication protocols? Contact our team today!