Req for building avr based plc

[avr_micro]

avr based plc

Dear masters

I want to start a project for building avr based plc,but i don't know how to start?Which parameters are more important?
I am working with avr microcontrollers since 2002 and also i know abit about plc.Is there anybody to guide me for starting point?Finally,is it possible to build an avr based plc?Of course i am not expected to build a plc such as S7 or Allen Bradly,just for building a simple mini plc with some timers and counters and coils and ... .

Regards

 

[umup]

avr plc project

First determine your requirements (how many analog/discrete inputs/outputs, what sensors to use, how much memory needed, does it need to be fully programmed or have integrated control logic etc...). I think ATMEGA16/32 or 64/128 must be anough
I have done several refrigerator/heater camera controllers (used ATmega16/32: 4/8 analog inputs for various sensors, 16-32 discrete inputs/outputs for motors/heaters/refrigerators/valves control). Program written in C (WinAVR)

 

[avr_micro]

build plc by avr

Hi.

For the most simple style:4 digital input and 4 digital output and 1 analog input.

regards