LogO & Stand-alone PLc

Join Date
Oct 2003
Location
Mansoura
Posts
46
Dear my friends,

it was long time sine the last sing in, I want really to know " Is there a difference between the LOgo, and stand-alone PLC.

Thnaks in advance
 
In my opinion the Logo and other programmable relays are essentially crippled PLCs. They are geared to a market segment that needs simple controls, with a few internal interlocks and timer and counter functions and not much else. They can be prgrammed without a PC software package. I've never seen much advantage for them, but for techno-phobic customers a "programmable relay" may be less intimidating than a "PLC".
 
The question is which is more suitable for your application
if u can get what u want with logo why not
logo now have the feature for pi control , multiplexing
also sometimes is a good solution if u want to use a circuit without having to use a dc power supply
 
If you are about to build yourself a simple panel, entirely on relay control with no PLC, then I would consider a Logo.
If you have simple application where the IO has to be intelegent enough to take over if the main PLC goes off line, then a Logo setup as an Asi slave can also do the trick.
It can also be used for controlling lights, or watering systems.
Its built in HMI panel, primative though it is, is also an excelent feature.
I consider the Logo to be at the lowest end of my automation "tool kit", however it does get some use.

Doug
 
The other day we had a motor to a conveyor belt go out.
The only replacement we had was geared way too fast.
We couldn't slow the VFD any more, and the gears were too difficult to change out.
We ended up using an Easy(which is pretty much the same thing as a Logo)driving the VFD using the jog input.
I ended up using a timer for on time and another timer in the "Easy" for off time.
They needed to change belt speeds for different jobs.
This way the operator could adjust the Off time by using the built in front panel on the Easy.
Although it's not a Stand alone PLC, there are times where it is just the right fit.
Good Luck
 
Logo and stand alone plc

Hi
I am sorry to tell you that Logo is not satnd alone plc
It was designed for small application and some analog inputs
Though in small applications it will work as stand alone there is difference between stand alone and Logo u can call it as Crip Plc.
 
This is how a guy from Siemens (a trainer btw) told me to look at the Logo! intelligent relay:
The Logo! is not a PLC because it doesn't scan the program as a PLC does, but is does it the way a microcontroller scans the program.
In other words: the Logo! reads the inputs and controls the outputs at the moment the relevant instruction is processed. A PLC reads inputs and controls outputs at a certain point in it's control cycle. A simple example to make this clear: figure yourself a set-reset (or latch-unlatch) combination where both inputs are true and the set is programmed before the reset. For a PLC the result will be that the output will remain in the off state. For the Logo! the output will be on during the time between the processing of the set and the reset instructions.

Kind regards,
 
As usual, Tom has described it very well. The "easy" and its repackaged clones (including the Logo, AB Pico, and many others) fill a need in the industry.

Back over ten years ago, the GE Smart Relay tried, in a slightly different form, more of a true programmable relay.

Unfortunately, some of the new "easy" type products are getting a little to pricey. Granted, you can shop online and find them under $100. You can get some fancier ones for a few hunderd.

You can also get a real PLC for a couple of hundred, and have a lot more capabilities. Entertron has the SmartPak series, AD has a couple of models, and other manufactuers too! Heck, you can even get a small AB for $99.

EZ's rack system is dirt cheap. I doubt I will ever use one, and don't know of anyone anywhere who has, to date. But they are cheap.

You can get a Logo, and it has built in software, to an extent. A stand alone PLC is stand alone, but you will have to support or assist it with an external programmer of some sort.

It sounds like the Logo, "easy", Pico, or whatever is more what you want, with it's built in programming capabilities.
 

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