Switching brands

We're considering switching PLC brands. We are considering Omron, Siemens, Allen Bradley and Automation Direct. We have virtually no experience with any of the above brands, and have only heard that Siemens are good but the software can be confusing, and that allen bradley is easier than siemens but the most expensive.

As long as the programming software is nice, I don't mind confusing at first. I probably heard that from someone who wasn't a programmer.

We have to bid to get our projects and nobody else is using allen bradley, so they're probably to expensive for us.

Projects generally have 500-1000 IO, of which 80% is 'in the field' so comes in to the PLC with modbus over ethernet on fiber.

Also have heard good things about codesys but am not sure what PLCs and remote IO solution to use that with yet.

Anyone have any platforms they recommend or ones to avoid!

The only requirements we really have is that on-line changes are a must, and so is a simulator so systems can be fully tested before they go out the door.

What brand do you use at the moment ? And why are you switching ?

Who has the best support in your area? Answer that question and your are 90% of the way there.

prefer not to say what brand, but pricing and procurement is the problem

Alaric's suggestion is an important factor. But if you have a good support I suggest Allen Bradley.

sounds like homework to me.

V0N_hydro said:

...................Projects generally have 500-1000 IO, of which 80% is 'in the field' so comes in to the PLC with modbus over ethernet on fiber.............

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If that's the case I would seriously consider PLC's that supported Modbus "out of the box". From memory Seimens & Rockwell do not they require additional software/hardware. have a look at which PLC's use modbus as a "native" language.

Why Modbus TCP ?

I strongly recommend that you chose the field bus that is native to the PLC brand.
That would be Profibus or Profinet for Siemens, Devicenet or Ethernet/IP for AB, and I dont know about Omron.
For a project with up to 1000 i/o and many in the field, I dont think that AD is a contender. AD also do not have a real online change as far as I know.

Hi.
500-1000 IO is not a small project. The cost of the PLC in something like that should be a small component of the life cycle of the project.
Support during development and for the next 30 years should be what the client is looking at, not wether he can save $5K at the start.

Hi Jesper. Unless AD changed their theory of how they do things then they don't have real online editing. They just freeze the outputs at the current state while the logix is being swapped around. Can make it very interesting in a factory when this happens.

Regards Alan

V0N_hydro said:

The only requirements we really have is that on-line changes are a must, and so is a simulator so systems can be fully tested before they go out the door.

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+ no pricing or procurement problems in the future

JesperMP said:

Why Modbus TCP ?

I strongly recommend that you chose the field bus that is native to the PLC brand.
That would be Profibus or Profinet for Siemens, Devicenet or Ethernet/IP for AB, and I dont know about Omron.
For a project with up to 1000 i/o and many in the field, I dont think that AD is a contender. AD also do not have a real online change as far as I know.

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FYI:- Omron supports Devicenet, Profinet, Ethernet/IP as well as their own Compobus and Componet protocols.

You write Modbus over ethernet. Yet Schneider is not in your list of brands. And that is strange since it is one of the large brands.

Is Schneider the brand you are using today? Otherwise have a look at it's Premium and Quantum family. The Unity software is good.

MrQ said:

You write Modbus over ethernet. Yet Schneider is not in your list of brands. And that is strange since it is one of the large brands.

Is Schneider the brand you are using today? Otherwise have a look at it's Premium and Quantum family. The Unity software is good.

Click to expand...

I have never seen a schneider plc in 20+ years. I guess it depend on what part of the world and what part of that country your in...

Dua Anjing said:

If that's the case I would seriously consider PLC's that supported Modbus "out of the box". From memory Seimens & Rockwell do not they require additional software/hardware. have a look at which PLC's use modbus as a "native" language.

Click to expand...

for a project that size I would just go with native protocol. with that many points I would prefer to not have to worry about doing any translation.

if you use AB you would have to buy a prosoft card then do all of the logic to support the conversion. thats gonna cost alot more than just buying a native driver... which may even be free depending on the scada package.

JesperMP said:

Why Modbus TCP ?

I strongly recommend that you chose the field bus that is native to the PLC brand.
That would be Profibus or Profinet for Siemens, Devicenet or Ethernet/IP for AB, and I dont know about Omron.

Click to expand...

Thanks for ruling out AD for us, that is good to know.

We aren't married to modbus TCP, it is just what we use now and what we are familiar with.

I agree with your recommendation to use the native field bus for the PLC brand.

Thanks for your thoughts