Re: PLC PAC operating system

antaresanto escribió:
On 27 Mag, 02:04, Paul Keinanen <keina...@xxxxxx> wrote:
On Tue, 26 May 2009 14:32:09 -0700 (PDT), antaresanto

<antaresa...@xxxxxxxx> wrote:
Does anybody know what's the operating system running on Siemens S7
PLC or other PAC ( programmable automation controllers ) by Siemens ?
A simple programmable logic controller simply

- reads the inputs,
- executes the control program and
- writes the outputs and then
- restarts.

You really do not need an OS for this.

Of course, some means are required to load the control program. Once
MS-DOS was a popular alternative to load the program from a floppy,
but these days any boot loader is capable of loading from flash.

Paul

Dear all ,
I mean an operating system because PAC ( and some PLC models ) have to
handle Ethernet protocols, complex serial protocols, complex
applications, some models also executes applications originally
written in C. These models are called usually PAC. Some models are
really industrial embedded PC. Does anybody know a link to PAC
operating systems overview ?
I know well that for reading inputs, elaborate and writing outputs you
don't need operating system.
regards

In our firm we made a PLC, functionally equivalent to an S5, in the late eighties. Up to 3 cycles, serial communications, multi-processor, etc. It had a proprietary, simple kernel, made by ourselves, in assembler. Nowadays there are firms like ISaGRAF (I think that's now the name of the product, not the company) that sell libraries from which you can build a PLC. If you look at the portings they provide, that could give you an idea.
.

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