PLC Market Comparison Chart

Does anyone know where to find a decent comparison chart for the different manufacturers PLC's on the market. Need to compare between Omron, Allen Bradley, Phoenix Contact, Siemens and Schnieder.
Need to know things like:
- Cycle times in milli seconds for 1K instructions for bits,words, arithmetic etc.
- program and data memory
- retentive data memory
- # of Instructions/internal flags/timers/counters etc
- # of I/O

anything at this point would be appreciated.

Thanks

Apples, Oranges, and homework assignments

Does anyone know where to find a decent comparison chart for the different manufacturers automobiles on the market. Need to compare between GM, Ford, Toyota, Honda, Mercedes and Peugot.
Need to know things like:
- Acceleration times in seconds for short trips on city streets, highways, etc.
- Dry weight at curb.
- Passenger and cargo volume.
- # of cylinders/ brake types/ headlights/ taillights etc.# of Instructions/internal flags/timers/counters etc
- # of passengers.


Now explain to me the problem with your question.

explaination to posted question

I know that different PLC's have different specs. What I'm trying to find out are those values so that I can see the differences.
example:
Siemens S7 400 412-2 Bit cycle time for 1k instructions is 0.1ms.
Phoenix ILC 370 is 0.06ms

Thats a value that can be seen as the difference right away. A chart stating those values is what I'm looking for.
If somewhere out there its already done then I don't need to re-invent the wheel.
Problem is there is no real criteria for all the manufacturers to specify the values at the same measure ex 1K Instructions.
example Omron says their cycle time for arithmetic is 8.2us
.....Based on 1 instruction I assume but the technical data really sucks for some of these manufacturers datasheets so what is it compared to the Siemens or the Phoenix which is based on 1k Instructions?

In terms of the scan time you are still trying to compare apples
and oranges. Overall scan time is a meaningless figure as applied to latest processors. For example ControlLogix platform allows you to set up periodic or continuous scan. You can allocate more
or less processing time to specific routines.
You should be looking at what it takes to process individual instructions. Also can the processor do event driven interrupts,
time driven interrupts and immediate I/O? Can you allocate more or less time to process overhead functions such as communications?
These features will determine how suitable a particular processor is for a specific application.
Modern processors don't easily lend themselves to simplistic comparisons.

Okay, kid, time for you to do a little work. Comb through the product catalogs for each of the vendors your specified and choose two actual models of controller.

For example, choose to compare the A-B ControlLogix with the Siemens S7-400 and the Omron CS1. Then maybe folks can contribute some useful data.

Who has a reason to create such a comparison chart ? The marketing departments of the various manufacturers, that's who. And they're never going to choose an objective reference standard, so you're on your own to evaluate the differing data you get.

The reason I teased you is that I saw you put very little work into your question. All the vendors you noted make four or more major product lines and you didn't even try to narrow it down, just like you couldn't compare F350 diesel trucks and Ford Focus subcompacts.

Also answer this simple question; are you selecting a controller or is this a class assignment ?

You can still get help from this Forum with homework, but only if you show some effort.

Well I guess what I'm looking for then is some sort of checklist of certain criteria/specifications that one would be looking for then the comparison can be determined from there.

example:

I need a PLC that can handle at least 6000 I/O , average scan time of mixed operations of 0.3ms and be programmed with IEC 61131 with program/data memory being 2/4 MBytes.
I see that Omron CJ1 series handles up to 2560 I/O so thats out. The CS1 series only handles 5120 so thats out too.
Plus both are only ladder logic not IEC 61131.

I see that Phoenix Contacts ILC 370 handles 8192 I/O..good there.
Can be programmed using IEC 61131...good there.
And has 2/4 Program/Data memory...good there too.

Thats the kind of thing I'm looking to compare. Just some basic specifications. I don't want to go too deep down the rabbit hole and be really application specific. Right now just looking to skim the surface and see whats what in fairly simple terms. It really doesn't seem to be too hard to me.

I know that Miles per Gallon on highway driving for a Toyota compared to a Honda will be different based on what kind of gas is used and whether the tire pressure is the same and whether or not the air filter is new or old but... I don't care about all that stuff I care about **BAM** what it shows on the spec sheet.
Toyota Carolla 8.4 mpg Highway driving
Honda civic 6.8 mpg highway driving.

Both had comparison of mpg and a number to compare.

Theres my difference!!!!!!!!!

Reply for Eddies response

Thanks for the feedback.

Thats mainly the issue. I look at the spec for Siemens Mid performance PLC and the Spec for AB Mid performance PLC and the spec for Omron Mid performance PLC and the specs are all over the place that I cannot decipher what the heck I'm comparing.

Its really not for classes its just overall.

Why buy the F350 if the job can be done using the Focus.

Why is everything in Automation related to cars?

Why would you want to control 6000 I/O with a single processor?
This makes no sense.

I'd also mention at this point, that 'controlling 6000 I/O' and bit-logic/mixed-logic scan time's have virtually NOTHING to do with one another.
You also need to consider the I/O update times. Some platforms do I/O updates synchronously to the 'cyclic' task scan, some don't. In synchronous processors, there is the additional time required to service the I/O... not much for the local rack, or 'local extended' racks, but it can be very long over a network.
With asynchronous CPU's, the I/O scan may be slotted and predictable (scheduled ControlNet, Polled DeviceNet, Polled Profibus), or unpredictable. Again, it totally depends on your platform.
Besides all that, execution time per instruction becomes nearly meaningless when you look at an actual program, and the method that each platform uses to scan logic.

Now you say you want IEC61131, but not ladder logic? LAD is an accepted 1131 format. Then again, if you must adhere to 1131, good luck. I don't know of any platform that is actually 100% 1131 compliant. Some come closer than others, but if you look up discussions of the 'standard' here, you will find many many issues.

Jiri Toman said:

Why would you want to control 6000 I/O with a single processor?
This makes no sense.

Click to expand...

I did this once with a PLC-3. Scan time was 200-300 msec.
But that was over 20 years ago.

The trend since then has been toward scaleable architecture and networking - e.g. ControlLogix.

Splitting a large I/O count into logical / functional sections with separate processors will normally give less total downtime and easier maintainability.

I see that Omron CJ1 series handles up to 2560 I/O so thats out. The CS1 series only handles 5120 so thats out too.
Plus both are only ladder logic not IEC 61131.

Click to expand...

Not true. The I/O count is only on base racks. Utilising Device Net etc will considerably increase the I/O count. For example, the CJ1M-CPU11 alledgedly only handles 150 odd I/O. One can use 8 Device Net Scanners on that PLC. 8 scanners times 63 I/O blocks times 16 bits is a hell of a lot of I/O on the smallest CPU in the range. 8064 digital I/O on the smallest CPU in the range? WHEW!!!!

Ladder is an IEC standard. The CJ1 and CS1 also use FB, another IEC standard. One can write FBs in STL, another IEC standard.

Cycle times for 1k words is really totally irrelevant the way you have asked the question. The only way you could ALMOST compare apples for apples would be to write a program and then look up each manufacturers information and total up the scan time.

Then different manufacturers have similar instructions that behave differently.

Then there is the Control Logix, as mentioned above.

Then there is the fact that different manufacturers have different amounts of memory used by similar functions (eg GE-Fanuc use 3 registers per timer or counter while others use dedicated areas of memory).

Then if you have an FB that is used many times in the program it is only stored as one instance in some PLCs and "called" when required thus vastly reducing the amount of memory used for FBs.

Then different manufactrurers have different ways of specifying the amount of memory available. Sometimes 20k in one brand equals 8k in another.

Then.... then....

I really do not know how one would prepare a comparison sheet these days. One also has to look long and hard at the way I/O can be used on different processors - refer to my reference to the CJ1M-CPU11 above as a small example.

By the way, I spent 25 years in sales and management with large companies that were selling PLCs and finished up the PLC "expert" with most of them. Also finished up doing technical support on seven brands over the years. I have yet to find a way to compare apples with pears.

Omron/ControlLogix comparison

Like so many others, I was a die hard AB user who thought they were the best around. We decided to research PLC vendors and brought them in to demo their equipment. We looked at 5 vendors. We decided to test the Omron CS and CJ processors and the AB ControlLogix and CompactLogix.
My eyes have been opened. If you have high-speed applications, tired of software-hardware compatibility issues, want much more speed and determinism, more power, more flexibility, more stability, and MUCH less cost, then you will be much happier with Omron.

Differences between Omron and ControlLogix:
* Omron can fit much more code in the PLC than CL. As a matter of fact, it takes 13-15 times more memory in CL to put a program from a SLC500 into it.
* The Omron CS and CJ can scan a fully loaded 64K processor with very complex code using many math functions, function blocks (both ladder & ST), indirect addressing, communication functions, and loops in 1mS or less. CL says that it is asynchronous and you can schedule routines and events. This reminds me of using control programs on a PC and time-slicing the processor with Windows. It all boils down to: someone will be missed. You can't run everything at the max.
* You can use Omron's CX-Programmer software to connect to and program any of Omron's PLCs from the largest CS to the smaller CJ to other modular PLCs to their VFD embedded PLC.
* You can also use an old version of CX-Programmer, imagine this, to communicate with a PLC that is years newer with changes to hardware, firmware, and instructions. You just can't use the new features until you upgrade the software.
* Many great development and diagnostic tools are built in to the Omron software and it never locks up or does something funky. With Logix5000 there are no PLC security built in, no program routine security is built in, no comparison tools, no clock update, no custom data monitoring. All of these are optional add ons. But there are many more tools available within CX-Programmer.
* You lose very little from Omron's CS to the CJ (less I/O, less specialty cards, same speed, same memory, same instruction set). You have a much larger difference from AB's ControlLogix to CompactLogix (less memory, less speed, no interrupts, can't backup and restore firmware & program from memory card, less I/O, less specialty cards).
* Omron's NS display has much more features at a much lower cost. Have any of you been through the PanelView+ fiasco over the last few years? I've gone back to the PanelView when I have to use them.
* I can get more performance, features, stability, speed, determinism, and at a cost of less than 1/2 price.

I can see now why Allen Bradley's market share in America has gone from almost 90% years ago to 40%. They are no longer the best out there, but they still try to price their components and software like they are. And, they still treat the customers like they are. I've seen the light and now I'm flying high. There's no comparison.

AB and Siemens both have SIL-2 certified options, does Omron have something like this as well?

Comparison by datasheets only isn't a good practice in this case. If you and your personnel haven't experience with this brand you can achieve worst result in comparison with using known equipment which has worse characteristics in datasheets. In case of 6000 I/O this isn't an option.