Choosing the Right Operator Interface Terminal

Picking Your OIT: How To & Best Practices

Selecting an Operator Interface Terminal for an application

This post will shed some light on how to go about picking out a graphical OIT. Let’s start with a definition: OIT = Operator Interface Terminal. Specifically, this post will explain the myriad of PanelView products available from Rockwell Automation. Choosing the right OIT isn’t often easy.  They are commonly used in batch and continuous manufacturing, and the applications can be quite intricate. Whether you are replacing an obsolete terminal or are looking at a new application, there are several considerations when sifting through your choices.

A Quick History of Graphic Terminals

The selection process used to be a lot easier back in “the day” when choices for a graphics terminal came down to deciding on whether you wanted a touchscreen interface or would rather operate the machine using membrane keypads and function keys. There was initially just one size available for that 50 lb, 12” diagonal CRT. By the way, Control Engineers loved them. Why Not? Gone were the days of hard wiring multiple rotary thumb wheel dials and seven segments LED panel display to I/O cards of your PLC. No more PLC ladder logic required to multiplex data to and from these devices of yesteryear. No need for number system conversions, i.e. BCD to binary and back. Yah, that was fun but enough of traveling around in Mr. Peabody’s WABAC “way back” machine. If you have a few gray hairs (or caught the reboot movie), you’ll understand the reference! 😊

Operator Interface Terminal PanelView OIT

Choosing the right OIT: Common Scenarios

What Operator Interface Terminal should you use? To best address this process we should look at a few basic scenarios. I would like to break it down into three different situations.

  1. What to do when replacing that cracked bezel, darkened screen, obsolete terminal that you’ve been using for the last 15-20 years.
  2. How about a brand-new project requiring a small and simple control system? (Say, less than 30 I/O points)
  3. Lastly, a more complex system requiring such features as extensive alarm handling and device diagnostics, remote and mobile device access, multi PLC communications, and comprehensive object libraries and face-plates. You get the picture.

Situation #1. Old and possibly obsolete

Operator Interface Terminal PanelView OITIn the first scenario, what you need to do is, first and foremost, get the model number of the unit. That alone tells much of the story such as size, communication options, power source requirements, color or monochrome screens, and whether it includes a touchscreen interface. The biggest issue with these legacy terminals is that they used legacy communication protocols to connect to the PLC. The newer PanelView™  OITs just don’t support the old serial protocols like DH485 or DF1. Nor do they include such peer-to-peer networks as DH+ or ControlNet. Even the device level networks like Remote I/O and DeviceNet have fallen by the wayside. It’s just a matter of evolution. Those communication methods can’t cut it in this IIOT world of data-hungry application software. Increase needs for real-time diagnostics, analytics, statistics, and products (okay I made that last one up!) has eliminated these interface methods. That leaves us with Ethernet running such protocols as Ethernet/IP, Modbus TCP, or Profinet. Ethernet/IP, of course, is the native protocol for Rockwell Automation products and the favored interface for all it’s newer PanelView terminals.

So, what to do when faced with this “old interface” dilemma? Ultimately, you may need to dig deeper into your control system and look at upgrading the programmable controller CPU and hence communication ports to Ethernet. That may be a little more to bite off than you intended but makes sense in the long run if you plan on keeping the equipment in use for a while longer. This said a more “phased” approach that’s easier on the pocketbook would be to use a protocol converter (a.k.a. gateway) in between the new terminal and the existing controller. There are lots available to go from Ethernet/IP to those legacy comm ports from companies like Prosoft or HMS Anybus.

PanelView Plus 7 Standard Graphic TerminalI would be remiss if I did not mention that the PanelView Plus 6 Graphic Terminals do support a number of these legacy protocols without the need of any gateways. They have a serial port for DH485 and DF1 and can still support the DH+ or ControlNet peer networks. They also include an Ethernet port which is handy when you eventually tackle that aging PLC. You just switch the interface port on the OIT to EtherNet when the time comes. However, sales for these products are soon coming to a close. So though this is a great option when faced with a downed machine, you will not have the luxury for much longer. That’s where using a PanelView Plus 7 (uses Ethernet only) and a gateway may make more sense.

Lastly, when replacing old for new, you do have to consider the software configuration requirements. Rockwell does make it easier when migrating from the “Standard” PanelView series (recognizable by the black bezel as all the newer ones are gray). The software used to configure the new terminals will import and convert the old file (PanelBuilder™ 32 format, AKA PB32). That software is known as FactoryTalk® View Machine Edition (ME). After importing the PB32 file, a few tweaks to the communication settings is generally all you need to do. Download the new runtime file and you are back up and running. The same is true when replacing a PanelView Plus terminal for a newer PanelView Plus 6 or, better yet, the PanelView Plus 7 series. Note that the development software may also need an upgrade to support the new hardware depending on the vintage or revision of the products you are using. A technical product specialist could assist you with that issue. Do you need assistance with OIT selection? Not sure what hardware may or may not be compatible? We can help. Contact our team today.

Operator Interface Terminal PanelView OIT


In the next post, I will go over what criteria is used when selecting an operator terminal for a new machine or project. A comparison chart will be made available that will summarize the feature sets for the newest product offerings giving you an “at-a-glance” understanding of the differences.

Situation #2. Brand-new project, simple control system

To be addressed in a future installment of this series. Check back soon for more Operator Interface Terminal insight.

Situation #3. Complex system, extensive features

To be addressed in a future installment of this series. Check back soon for more Operator Interface Terminal insight.


Do you need assistance with an operator interface terminal selection? Not sure if your hardware is compatible? What types of legacy OITs are you using?

 

About the author

Dan Simpson
Dan Simpson

Dan is an Automation Specialist who focuses on improving manufacturing processes through efficient solutions. His areas of expertise include programmable controllers, HMI, and motion control systems. Dan brings over 30 years of controls design experience and a thorough understanding of both existing control systems and the latest technological advancements in industrial automation. Folks in Maine have told us that they enjoy working with Dan because he listens well to their issues and presents himself in a friendly manner.