Automation Vs Embedded Systems.

Hi guys,

Just a little thought came into my mind regarding automation and embedded systems, i learned PLC programming and when compared with embedded technologies, the applications are same like we can make car parking, elevator, and many other application in embedded as well as PLC's then what is the difference between the two, is it only languages and hardware connections used or something else is there.

what u guys think....

PLC's are expensive, usually much larger than an embedded system, and are less robust. PLCs are usually designed to be used for testing/automation of a single product (cars), where as an embedded system can be easily modified to work with multiple projects without having to change any circuitry (only the code running on the microprocessor).

The hardware involved in both are similar, the software on the other hand is completely different. Embedded systems use mainly C or systemC, and in some cases VHDL/Verilog where as PLC programming uses ST and other things like that.

Some general comments/observations:

With a PLC, the manufacturer has already designed the hardware all the way down to signal types and connectors.
With an embedded system you can develop whatever you like in terms of hardware.

With PLC's inputs/outputs can be swapped around using pre-configured modules to suite the design - and later changed without to much consideration. Embedded boards take up less space however are quite specific to a design.

Software for a PLC is typically tied to a specific PLC manufacturer - you use their implementation of PLC logic on their hardware. (although IEC standards are now helping).

With embedded you can use whatever level of software (and standards) you like - such as high level 'BASIC' or low level assembler or something in between like C.

With embedded you require experience or knowledge of electronics to some degree, with PLC you are removed from this to a degree as the manufacturer has done this part of the design for you.

If your application is required on hundreds or thousands of systems then embedded in the longer term would probably be less expensive - but you would have to tool up for it. If your application is required on less than say one hundred systems then PLC may be the route to use.

PLC's are in general very fast at processing inputs/outputs without any custom software development. There are PLC's that can operate with redundancy, with millisecond response to failure.

PLC's have multiple communications interfaces and protocols predefined - with embedded you would have to source test and prove your interface. You might have to get external approval certification to prove your interface complies a standard.

PLC's can be purchased that already meet industrial standards, electrical standards, suitable for marine applications, industrial environments. With embedded you would have more responsibility to ensure you comply and then get certification.

Horses for courses as we say here..

Then we can say going for embedded first and then catching up with plc would be good rather than automation first and embedded next.?