Useful features

I work for a firm that’s tied down to just a couple of older PLC types. Looking to the future I’m wondering what features particular brands have that are very useful that others don’t do. We’re likely to be looking at the bigger suppliers, RA, Siemens, Schneider, Mitsubishi etc...

Reading similar questions on here I’ve come to the conclusion that the hardware is fairly comparable between them all. I noted that Contrologix can do hot card swaps, and Schneider don’t have backup batteries. I don’t know much about Siemens really.

I suppose it’s a bit like a dream team I’m trying to build. What features could you draw from all brands to make the ultimate offering? I want to work out what is useful from a specification point of view.

It’s a slow moving process we control. Analogue and digital I/O - no motion control, very little intelligent instrumentation and drives (we’ve been using profibus for this where we have it)....

Thanks for any input

Andy

I'd go with Siemens... Their offering in hardware is great and most vendors work with their main protocols (Profinet/Profibus). If you already have profibus network, a brand new Siemens PLC still supports Profibus out of the box.
The programming software for PLCs is far cheaper than Rockwell.

Siemens has a PLC Simulator that is light years from anything else in the market. So for the most part you don't need hardware to develop. Rockwell tried to have something similar but it's so limited that it's as good as useless.

On software development, I very much prefer Siemens as it gives you more options to break the code in manageable bits and maintain it. Rockwell (for my taste) is not as good on that front. But this is down to some personal level. The biggest let downs for me on the rockwell programming is the visualisation of the code (there's way too many ways to hide things from the user) and not being able to change AOIs online. I'm not too keen on having all variables in the same space without a way to easily segregate them (Siemens has datablocks and you can store them in folders), but it's not that big of a deal.
A lot of people will say that Rockwell's ladder editor is the best... although I agree that it is, I would very much prefer to be able to download a subroutine or AOI instead of doing online changes which is somewhat convoluted and in older processors a right pain as it may not have enough memory.

One thing that I like with the Siemens kit is that there's network cards available for their mid and upper tier PLCs. Rockwell only offers this for the upper tier and it's a bit **** if you want to have a SCADA network and a DLR that are segregated.

A downside of Siemens is that the communications drivers for SCADA (unless their own offering) is still based on datablock addresses which, although not being a deal breaker, is not as nice as what EthernetIP usually offers. On the other hand, if you're to link these PLCs to a new SCADA, I'd look at using OPC UA which new Siemens PLCs talk.

In terms of support, there's an extensive network across the UK for siemens. Although Rockwell isn't bad, it's not as good. Rockwell however will take on actual project development for you. Siemens has a threshold of 2 or so millions. This being said, Rockwell's terms for projects aren't great for smaller projects and you can usually do a full installation with a Siemens certified integrator for the cost of Rockwell hardware.

Siemens doesn't use batteries anymore.

+1 for siemens as above

Thanks for the info, it’s much appreciated. I’ve never used any of these bang up to date formats - we are firmly stuck in the past at the moment!

I’ve also been looking into options for converting RSLogix 500 into newer formats, we have a lot of these.

Obviously there is the Rockwell route using compactlogix, and they seem to have some kit to take the existing SLC plugs, but from memory these sit behind the new unit - which doesn’t seem the best idea.

I can’t see any option for this kind of thing with Mitsubishi.

I watched a YouTube video of someone doing a a conversion into a Schneider Modicon M340? PLC, and that looked quite good, plus the SLC connector plugs went onto the front of the new I/O with an adaptor.

Do Siemens do something similar?

andy_1983 said:

Thanks for the info, it’s much appreciated. I’ve never used any of these bang up to date formats - we are firmly stuck in the past at the moment!

I’ve also been looking into options for converting RSLogix 500 into newer formats, we have a lot of these.

Obviously there is the Rockwell route using compactlogix, and they seem to have some kit to take the existing SLC plugs, but from memory these sit behind the new unit - which doesn’t seem the best idea.

I can’t see any option for this kind of thing with Mitsubishi.

I watched a YouTube video of someone doing a a conversion into a Schneider Modicon M340? PLC, and that looked quite good, plus the SLC connector plugs went onto the front of the new I/O with an adaptor.

Do Siemens do something similar?

Click to expand...

Personally, I've never seen IO adapters as a sustainable approach. To me it feels like one more thing to break down the road, and would be difficult to troubleshoot. I know minimal upgrade downtime (precious production uptime) is always a priority, but that might not be the way to go about it.



To one of your earlier questions, Siemens can do card hot swaps to replace defective cards, depending on which IO you use and how you set it up. However, making an actual CHANGE (like adding a card that wasn't there before) to the HW usually requires the PLC to stop. There is IO available for the main rack, but it is fairly common to utilize a PLC sitting by itself and a remote IO panel sitting under it in the same rack, communicating over Profinet.



It might take phases, but if you're modernizing, I'd recommend pushing to go all the way to a modern system. Nothing against Profibus, but you want that all to be on some kind of Ethernet fieldbus (profinet, ethernet/ip, etc) if possible. If you go half measures to simplify now (save money, faster implementation, whatever), you'll have a lot less flexibility moving forward, and miss out on a lot of the advantages of the newer HW.

andy_1983 said:

Thanks for the info, it’s much appreciated. I’ve never used any of these bang up to date formats - we are firmly stuck in the past at the moment!

I’ve also been looking into options for converting RSLogix 500 into newer formats, we have a lot of these.

Obviously there is the Rockwell route using compactlogix, and they seem to have some kit to take the existing SLC plugs, but from memory these sit behind the new unit - which doesn’t seem the best idea.

Click to expand...

You can convert the RSLogix software to a Siemens S7-1500 or 1200 plc, done a few of these now and the conversion is excellent....

RA is far too expensive now compared to siemens and TIA Portal and the siemens kit is far superior to the RA stuff - I used to use lots of RA but those days are long gone......

Everyone has their own preference.
May i suggest that you look in your area for plc distributors.
meet with them and discuss your needs, look at their stock on the shelf.
what is their reputation?
if downtime is critical, make all the plc's the same model number and have spares. our stock room has enough spares to build several plc's.
the next thing i would look at is what software do you have for plc's, what is maintenance used to?
a different plc may be cheaper, but the software, pc requirements, compability with existing software, learning curve, and downtime may be the deciding factor to keep the existing brand. request the plc distributor to give you a demo unit and laptop to try the software out. you may have to go to their place to do this.
james

I really like the Schneider M340 stuff for smaller and medium systems. The software is reasonably priced. The Ethernet Remote I/O situation is strange. They threw together a stripped-down version of their CPUs and labeled it as an Ethernet remote adapter.

Allen-Bradley software and support is like quicksand. You slowly sink into it and by the time you feel trapped you are.

A big thing for me is IEC-1131 compatibility. Rockwell was dragged kicking and screaming into 1131 and they haven't stopped struggling. Their 1131 compliance isn't as good as other people. Their communication protocol is superior. It somewhat becomes a choice of what is most important to you - language vs protocol.

Many people sing the praises with AB ladder because it is familiar. The unfortunate thing is that they do not distinguish the quality of the editor from the quality of the language. The AB editor is the best I have ever seen - it blows away the Schneider editor. The AB ladder language is another story. There are a host of things I don't like about it. It suffers from some code versus data issues that AB has had for decades. I may be in the minority but I'm an advocate of strict data typing, etc, etc, etc. The 1131 people had reasons for what they did based upon decades of experience with computer languages. We should not ignore that based upon a perception that there is 'too much to think about and type in' with 1131.

Schneider has acknowledged ABs superiority with protocol issues. They're using a lot more Ether/IP in their products.

The best of luck to you.

I really like the Schneider M340 stuff for smaller and medium systems. The software is reasonably priced. The Ethernet Remote I/O situation is strange. They threw together a stripped-down version of their CPUs and labeled it as an Ethernet remote adapter.

Allen-Bradley software and support is like quicksand. You slowly sink into it and by the time you feel trapped you are.

A big thing for me is IEC-1131 compatibility. Rockwell was dragged kicking and screaming into 1131 and they haven't stopped struggling. Their 1131 compliance isn't as good as other people. Their communication protocol is superior. It somewhat becomes a choice of what is most important to you - language vs protocol.

Many people sing the praises with AB ladder because it is familiar. The unfortunate thing is that they do not distinguish the quality of the editor from the quality of the language. The AB editor is the best I have ever seen - it blows away the Schneider editor. The AB ladder language is another story. There are a host of things I don't like about it. It suffers from some code versus data issues that AB has had for decades. I may be in the minority but I'm an advocate of strict data typing, etc, etc, etc. The 1131 people had reasons for what they did based upon decades of experience with computer languages. We should not ignore that based upon a perception that there is 'too much to think about and type in' with 1131.

Schneider has acknowledged ABs superiority with protocol issues. They're using a lot more Ether/IP in their products.

The best of luck to you.

You stated you have a couple of older type PLCs. What brands? What is the range of complexity of your existing programs? As some have suggested, contact different suppliers to see if one platform/processor will cover all your applications. My concern would be the support cost after the hardware changes have been made. Who will program it? Is your existing maintenance staff able to use/learn it quickly? What about spare cards, PLCs, HMIs etc. The cost of carrying components for multiple platforms can be enormous. Mind you, not as expensive as NOT having the part on the shelf....let us know the path you choose and any unforseen benefits/problems you found...

andy_1983 said:

Thanks for the info, it’s much appreciated. I’ve never used any of these bang up to date formats - we are firmly stuck in the past at the moment!

I’ve also been looking into options for converting RSLogix 500 into newer formats, we have a lot of these.

Obviously there is the Rockwell route using compactlogix, and they seem to have some kit to take the existing SLC plugs, but from memory these sit behind the new unit - which doesn’t seem the best idea.

I can’t see any option for this kind of thing with Mitsubishi.

I watched a YouTube video of someone doing a a conversion into a Schneider Modicon M340? PLC, and that looked quite good, plus the SLC connector plugs went onto the front of the new I/O with an adaptor.

Do Siemens do something similar?

Click to expand...

Siemens dont do any connector to convert from using plc plugs - which in my opinion is a bit of a bodge - just rewire to a new module (Siemens, AB whatever).

The ET200SP siemens series supports single and multiple hot swopping of the modules - see their tech sheets.

What part of the uk are you in ? Parmley Graham would be your best bet for siemens distribution..... They are very good (at least my local branch are)

Hi, again - thanks for the information and ideas...

Our existing asset base is heavily PLC5 / SLC & Mitsubishi. There’s a handful of really old ones like Texas and square D but these are not a concern really. We have to come up with a spec for what we want from our controllers and then go out to tender for it, so at that point the potential suppliers can demonstrate their wares.

I was really looking to see what the latest offerings are so we can target the areas we want to develop.

from what I’ve seen of logix5000 it has the look of logix500, but I know it’s significantly different. Also, with the Mitsubishi stuff we’d be looking at GXWorks 3, and that’s significantly different to previous Mitsubishi software. Moving away from what we know wouldn’t be too bad, as there’s going to be a learning curve with each option

I’m probably more worried about comms between the old and new stuff when they’re installed together, I’ve got some more digging to do around this.

So far there’s been some good info, so thanks...

I would stay with Rockwell they have a big lead in technology
the Control Logix dose support hot swapping but I do not recommend it on any PLC
i have seen to many times the back plain was damaged doing it it's just not worth the risk.
Some models use Battery backup and other do not need it so its a matter of you your choice.
their processing speed is faster then most others an a good verity of IO modules to select from
they have been around for a long time and i expect them to be around well into the future
they also support a good migration plan to upgrade their systems

I've done one SLC5/05 to Schneider M340 conversion. 180 I/O for a small water treatment plant. Schneider did the code conversion for us using a software tool they developed. It worked OK enough to get the plant running again quickly but i ended up re-writing a lot into FBD since the Schneider ladder editor is terrible.

We didn't use the wiring adapters as we had some high density 32 point dig ins and outs and they didn't have an a solution for that, the wiring adapters were only for 16 point cards. I rewired everything myself in 12 hours (planning and pre-fab or wiring looms is the key).

I personally like Schneider's M580 platform with ethernet remote racks or STB remote I/O. Have not used Siemens but have a colleague from South Africa where they used a ton of it, that always tells me it's light years ahead of this Schneider rubbish I keep building his plants with. I guess it does often come down to what you know and are comfortable working with.

If you have to get some legacy stuff talking to new stuff during the migration process, I'd highly recommend something like a Red Lion Data Station Plus to act as a protocol gateway. Use it to swap data between say DF1 on your SLC and modbus TCP on a Schneider PLC/ keep SCADAs working until everything is modernized.

Brownfield projects are often the most challenging when it comes to this kind of thing.

andy_1983 said:

I’ve also been looking into options for converting RSLogix 500 into newer formats, we have a lot of these.

Obviously there is the Rockwell route using compactlogix, and they seem to have some kit to take the existing SLC plugs, but from memory these sit behind the new unit - which doesn’t seem the best idea.
I watched a YouTube video of someone doing a a conversion into a Schneider Modicon M340? PLC, and that looked quite good, plus the SLC connector plugs went onto the front of the new I/O with an adaptor.

Do Siemens do something similar?

Click to expand...

Both Rockwell and Siemens do conversions of old AB code into their new standard. My advice is not to bother with it and instead take the short term pain of a newly written program for long term gain in maintainability and ability to expand the system.

This is from someone that made the terrible mistake of converting a PLC5 program to TIA Portal and it was an awful result. Yes, the machine works the same as it did before, but finding anything in that program is 2 times harder than if it had been written properly.