All-in-one PLCs

This is in response to Stephen Luft's comments elsewhere about all-in-one PLCs in general, and Unitronics in particular - I didn't want to hijack the thread

Stephen referred to a white-paper published by Entertron which made the following statements regarding such controllers:

>>All wiring terminates to the door of your enclosure, unlike the separate PLC and operator interface products that have two connections: one for the serial port and one for the power cable. There will be a huge wiring harness going to the door of your panel.<<

Now, this can happen. Personally, I don't like having a large cable running to my door, so I use expansion IO instead. A single 4-conductor data cable to my expansion adapter and away I go.

On the other hand, you don't strictly HAVE to mount your Vision 280 on a door. I find they work outstandingly well with a floor-mount pedestal.

>>The output rating will be less than the traditional PLCs and far less than Entertron's controllers due to board size and component ratings constraints.<<

Like my tax guy told me when I wanted to know if I could write my free-loading brother-in-law off as a dependent - "it depends". The E3B snap I/O has 3 Amps max for a resistive load, and 8 amps max per common. I believe this is on-par with most micro PLCs. And since I always use interposing relays (God Bless Phoenix Contact) it's pretty irrelevant to me anyway.

>>Possible replacement will be challenging in that you will have to remove the entire controller / operator interface<<

This is true with the smaller Uni lines, the M90/91 and Vision 120. The larger units use Snap IO, so if you fry one, just replace the module- it "snaps" on and off.

As for the smaller units, they all work with the same expansion IO, and as stated previously, I use that for the most part anyway.

>>One processor for both the operator interface and PLC greatly reduces the scan rate of your application.<<

Now there is some truth to this one. Unitronics PLCs have a slow scan rate owing to the need to update the HMI as well as scan the ladder. BUT! They are improving this all the time. The latest OS provides a 30% speed increase over the previous, and in any event, I've yet to encounter a job where the scan time was an issue anyhow.

In a nutshell, I like Unitronics for alot of other reasons besides the all-in-one thing. I like lots of options. I like free software. I like buying an entire PLC and HMI for half the price of some people's HMIs alone. I like free support. And I like ethernet connectivity for $110 US, instead of $500+. There's alot to love here besides the physical architecture of the system, which I can take or leave as needed.

Lastly, let me tell you, these suckers are durable. I've got two M90's I bought for $250 three years ago that are now in their third machine application, and still going strong without a hitch.

So, with all due respect to Mr Luft (nice guy, no complaints from me) I think I'll stick with my Uni! And that's my two bits.

TM

Timothy,

It is always a good thing to have people respond to your posts, especially when you do two bits as opposed to two cents, that is 12.5 times more input...

With regards to some of your information:

So, if you are using expansion I/O that is not part of the entire package, then it really isn't an all in one solution. A ribbon cable, compared to a serial cable. The only advantage then is one programming for both. Then as stated later on, the update rate is slower. The disadvantage of one processor for two functions.

As you had stated with the Unitronics, they are on par with others. Let's look at the other output ratings:

Relay outputs:

Unitronics - (M91 & Visual) 5 amp resistive, 1 amp inductive
(E3B - 3 amp resistive, 1 amp inductive) - as you have stated
EZ Automation - 1 amp
Horner OCS - 2 amp for 20 outputs or 4 amps for 8 outputs (module dependant.

Separate Micros - typically 2 amps / output


Transistor Outputs:

Unitronics - .5 amp
EZ automation - .5 amp
Horner OCS .5 amp

Modular tend to be from .1 to .3 amp range
Bricks tend to be in the .5 amp range

Triac Outputs:

Unitronics - N/A
EZ automation - 1 amp
Horner OCS - N/A

Very few manufacturers offer a triac output. Typical ranges for those that do are .5 amp

Keep in mind this was very general. Some products have special modules with higher ratings, but they tend to have fewer points of I/O, so it can be a trade off.

I would say that they are on par with the other manufacturers as opposed to being less than other separate products, from an output rating perspective.

It is good to see that Unitronics does some of the things that should be done regardless...the free software and support, always a plus.

God Bless,

For the most part, I never have leaned towards all-in-one units. With a PLC and a HMI, the machine will probably still run without the HMI attached, Maybe with the laptop plugged in.

I had considered using a small all in one on the panel door and use an expansion module or network to another plc. It just doesn't seem practical. I guess I will lean towards a MMI, and let it go at that. Seems like it would be a lot of personal preference. I know that some of the generator control panels get a little wicked with 20-40 panel lights, 3-6 meters, and a gaggle of switches, Makes a real nice bundle of wires to fight everytime the door tries to close.

Perhaps mounting an all in one on a pedistal is the way to go. We did a lot of controls and switchgear years ago that were deadfront. some were open in the rear, some had doors back there. They weren't to bad to work on, and sheet metal was in house at the time, and they did a better job than usual with them.

I have mounted some small HMI's on the end of a cabinet, that may work very well for all in ones. No wire flexing, and the door opens up very conveniently. Something I'l try to remember to consider in the future.

It will be interesting to see if Entertron comes out with an all in one. Since their TRIACS are at 2 amps, and Relays consirably higher, that might make for a nice hefty unit. If they used smaller outs, which I would seriously doubt, they would still probably have higher current ratings. We look forward to your announcement, Stephen.

regards.....casey

For the most part, I never have leaned towards all-in-one units. With a PLC and a HMI, the machine will probably still run without the HMI attached, Maybe with the laptop plugged in.

Click to expand...

YEP!!! My applications are too critical to have a HMI get busted and the whole system stops. Can you imagine no emergency power available (generator) for a large transimission provider because a HMI got busted. One large one in Sydney handles all the data from Sydney Airport to all over the world. If 2 out of 4 UPS units go into bypass, start diverting planes, let alone no backup generators. NO THANKS!!! Too many people around with screw drivers to press the buttons on the HMI. Have had that happen several times.

>>The output rating will be less than the traditional PLCs and far less than Entertron's controllers due to board size and component ratings constraints.<<

Click to expand...

Could not care less. Just about always use transistor outputs to drive whatever I want, relays, triacs, larger transistors. Got sick and tired of trying to replace PCB mounted relays in the middle of the night because a solenoid blows up and takes the PCB mounted relay with it. Costs a little more but the relay is a heck of a lot easier to replace.

External relays generally have a larger air gap, if you pick the right one. Can be quite important with DC systems where air gap can be critical for putting out the arc.

Thanks for the replies!

One concern voiced here was the ability to run without an HMI if needed. In response, I offer this for consideration:

If you have spare parts, you likely have an HMI. If you don't, you should

That said, a cetain manufacturer who shall remain nameless currently offers a monochrome touchscreen of the same proportions as a Unitronics Vision 280 for $1865 - PLC and programming software (for both)sold seperately. In contrast, the V280 offers the same HMI with PLC included for $699, with free software.

Now, if we add I/O to comparable levels (base unit/snap IO and 2 expansions each), ethernet modules for both, and software costs, the initial purchase of an entire PLC/HMI system from Unitronics is $1429. For nameless, it's $4641.

To circle back around to the original question: if you are going to stock spare parts, which has more value to you sitting available on your shelf? An HMI for $1865 or an honest-to-God complete control system for $1429 (bearing in mind that a comparable system from the HMI guys will run 325% more than that)?

Thoughts?

TM