Which brand PLC's play best with Ignition?

I run Ignition with a GE RX3i PLC and 15 remote I/O racks plus one Siemens PLC (in an OEM package) in a pilot plant/laboratory environment that I own. I am looking to specify Ignition as the SCADA system for a full scale plant we are designing. The final I/O count will be 10-15,000 and the plant will be a 24/7 processing plant (mining industry).

I am after recommendations for what PLCs play best with ignition, ideally without the Kepware interface. It’s a new build so I have no legacy systems to worry about. My main concerns are ease of configuration, spare parts availability, robustness and remote access as it will be on a remote mine site. Up front budget is not such a big concern if it saves me up front engineering time and is easy to implement.

Thanks in advance,

Ignition natively communicates with a number of PLCs as listed on their website such as Alled Bradley, Siemens and Omron. It can of course communicate with any PLC with OPC onboard or, as you’ve suggested, using an intermediate OPC Server. I’ve found the most user friendly PLC’s to be Allen Bradley’s as Ignition can broswe tags, and drag and drop them into the project. You can also do this with any device with an OPC servers, but the AB PLCs don’t need this. The GE PLCs will probably require a seperate OPC server.

Allen Bradly also has a reputation of being robust, reliable and quite easy to source. They do cost a bit more than some alternatives though.

To save engineering costs, I recommend you use an experienced Ignition integrator. There are 20 ways to do the same thing in Ignition so you need someone who knows the most efficient way forward.

It depends a bit on your region though. If you’re based in Europe, PLC brands like Siemens or Beckhoff are easy to source too.

As David said, any PLC with an OPC-UA server on board is pretty easy to configure (you can drag-and-drop tags into Ignition). Other PLC’s are often also compatible with Ignition, but may need a bit more manual typing to copy all the addresses.

1 Like

Thanks David and Sanderd, Good to hear that Allen Bradley, Seimens Omron and Beckhoff are all able to work as described. I asked the question because of past experiences (mainly with a wide range of GE products and some Yokogawa DCS) of things not doing what the vendors say they will do, or it being significantly more time consuming or costly.

Even inside the brand you choose, you will have to select the correct configuration. Like w.r.t. Siemens, their lower end PLC’s don’t support OPC-UA. And for Beckhoff, you need an extra license to get OPC-UA support.

But your vendor should be able to tell you if OPC-UA is part of the deal or not.

My vote is also for any PLC with an onboard OPC UA server.

Siemens, Omron, and Beckhoff have all been doing this for a while now. Rockwell is years behind. I’ve seen a GE PLC with an onboard server at an interop event some years ago but I don’t know how you actually go about acquiring one.

Oh, and Bedrock PLCs have onboard OPC UA and tend to work pretty well with Ignition as well.

Newer CompactLogix and ControlLogix don’t have an OPC UA server yet but Ignition’s driver is generally a good experience. The new protocol they introduced in firmware v21+ doesn’t perform very well, so if you need a lot of tags it’s not that great, but the fancy L8x models have a dedicated CPU for communications and that helps a lot.


Do the PLCs with on board OPC UA Communicate with ignition server as opc server without a driver ? It’s hard to believe that Rockwell , a leader in PLC doesn’t have an on board OPC ! Their PLCs integrate with ignition smoothly, allowing a Tag browse Capability ! Perhaps they provide a good driver API.

I guess Siemens new series 1500 onward only have On board OPC. The older ones like 300 , 400 didn’t have it ! They are the big time supporter of OPC in my opinion .

They provide a lot more information if you are an Encompass Partner.

1 Like

We have sites with over 100,000 tags across multiple Rockwell PLC at various firmware levels and have very few if any issues using Ignitions OPC server.
Granted you have to configure your scan classes properly and pay attention to load, memory usage, communication time slice in older PLCs etc.
I will agree about the L8X series, they are a Godsend for communication heavy environments.

1 Like

They don’t communicate with Ignition’s OPC UA server at all.

You configure an OPC UA client connection to the server on board the PLC just like any other OPC UA server, including Ignition’s own.

Yes that’s what I meant. Ignition has both OPC server and a client, the later communicating with the on board PLC OPC.

FWIW I have worked with Emerson (formerly GE) Rx3i systems with CPE305’s and used the on board OPC servers to successfully broadcast tags directly to very small test Ignitions systems. Emerson seems to be actively addressing OPC in their systems (EG the max number of published tags has increased dramatically with new firmware releases)

IMHO the main caveat is that when importing tags into Ignition there is NO hierarchy. You get all the tags you have marked for publication in alphabetical order in one big batch. This was bad enough on a small project but I can’t imagine what it would be like on a real system as on the Ignition side there seems to be no way to filter tag names when searching for the appropriate tags. (I vaguely remember seeing a request for filtering OPC tags, but the request was shot down). I don’t have any experience with other PLC brands to know if it is also an issue with them.

I’d also be careful if you are using redundancy as I have seen issues with with it on teh CPE305 when combined with OPC.

Ouch; I can’t imagine working with that. UDTs mean we have many tags that are named identically, aside from their hierarchy. Beckhoff TwinCAT 3 (skip TwinCAT 2) is pretty easy to work with when you know it and their TwinCAT OPC-UA lets you browse/import tags with all the expected hierarchy. You specify in the tag definitions in the PLC which ones to make accessible read-only or read/write or not at all via OPC-UA. Doing this filtering reduces the load on the PLC and shortens the list of tags to browse through in Ignition, so I’d recommend it as part of the programming.

Beckhoff parts aren’t as accessible in NA as Allen-Bradley (some have lead-time of a week or more), but we’ve found them reliable and prefer them to Allen-Bradley (which used to be our preference). That said, we program them primarily in structured text. If you want to stick with ladder logic, I would go with Allen-Bradley.

Thanks everyone for their input, it’s greatly appreciated.


Their SCADA software is even further behind…
However their PLC software, at least in my experience, is fantastic


I wonder why they are so behind in opc! Looking at opc foundation’s ambitious plans, looks like going forward its going to be a must for not only controller but even for all devices to have it embedded in it. After all its not a big foot print software in my opinion.

OPC-UA isn’t that lightweight on the hardware either. For lighter processors, it can be quite an issue.

But the problem with Rockwell is that they have a monopoly in the US. On one hand, it makes their products very well available (which is a must-have for many industrial environments where downtime is costly). But on the other hand they aren’t pushed to innovate.

1 Like

I think one can pick and choose a profile in opc stack one want to build, so its not necessary to build full featured server and offer a light weight server. In principle it obviates a lot of interoperability and connectivity issues once you an opc compliant product. Perhaps they may have plans to offer it in their newer products in future. We don’t know their road map and priorities and business decisions.

Concur. OPC/UA may be the best choice for interoperability, but it is not a great solution for typically wimpy embedded devices. Wimpy by design to enhance robustness, lifespan, and harsh environment endurance. Overdoping on larger chip surface features is an an absolute requirement for long lifespans. Semiconductor physics is particularly unforgiving (dopant diffusion) at elevated temperatures.

Hah! I see lots of brands in use among my customers. Definitely not a monopoly.

Uhm. I beg to differ. Their Logix architecture is fantastic, and continuing to evolve in ways that customers appreciate. And it has a very well-specified, browsable, query-response protocol and a very well-specified producer-consumer protocol. Robust and now proven in use for over two decades. I would argue that Ethernet/IP’s feature set, in a publicly available form (Rockwell’s spin-off to the independent ODVA) has forced the OPC Foundation to catch up.

Ethernet/IP is also practical to implement on wimpy devices. I think OPC still has catching up to do. Wide adoption of Ethernet/IP on non-Rockwell products is not an accident.


I’m not meaning to bash on some brands, but it’s interesting that we can buy an AB PLC in Belgium, ship it to the US, pay import taxes, and still end up way cheaper than buying it directly in the US.

Even if they don’t have a monopoly over all the US, they’re clearly more worried about European competition than competition in their home market.

1 Like