Newbie seeks help designing a plc ciruit.

[Zardoz]

OK. Dunno if I'm talking to the right people...


I need to build a circuit based on a plc that

1. Is programmable from a PC via serial

ie Set parameter X=20000
Start
and Stop operating

2. Operates independently of the PC
3. The program it runs has two inputs and one output. One input is
from a sensor. The second is from an encoder which provides pulses
(proportional to the rotation of a shaft).
4. After a predetermined (ie X) number of pulses, send an output.


I reckon this is an easy one but I don't know where to start. Any
clues? I think what I want to know is a cheap plc type device and lots
of help

Thanks

 

[Anthony Fremont]

OK. Dunno if I'm talking to the right people...


I need to build a circuit based on a plc that

1. Is programmable from a PC via serial

ie Set parameter X=20000
Start
and Stop operating

2. Operates independently of the PC
3. The program it runs has two inputs and one output. One input is
from a sensor. The second is from an encoder which provides pulses
(proportional to the rotation of a shaft).
4. After a predetermined (ie X) number of pulses, send an output.

What will the sensor do then?

I reckon this is an easy one but I don't know where to start. Any
clues? I think what I want to know is a cheap plc type device and lots
of help

What you want is a microcontroller. PIC, 8052, AVR or even a BASIC
Stamp; take your pick. I prefer PIC chips myself.
Look here:
http://www.voti.nl/pic/index.html
http://kahuna.sdsu.edu/~tucker/pic/
http://www.8052.com
http://www.avrfreaks.com
http://www.parallax.com/

 

[tkirk]

The company I work for, Rogue Engineering Inc., designs equiptment for
use in industrial controls. One of our products is a smart I/O board
that can double as a simple PLC. We sell it along with PC software for
setting it up for around $200, which is cheap by PLC standards. Email
[email protected] if you're interested. Include specifications on
what the inputs and outputs should do and we'll make sure to load in
firmware that handles that task.

If you're looking to design a circuit yourself, for a hobby or school
project, then I would recommend looking at PIC microcontrollers.
They're not as powerful or cheap as some of the microcontrollers I use
at work, but they have a lot of support information out there for
hobbyists, and free/cheap tools for when you're writing and debugging
your firmware.

Tim Kirk
[email protected]
Electronics Design Engineer
www.rogue-engr.com