Quote Originally Posted by MikeHolm View Post
PIC, yet another skill to learn. I have been making control panels from relays for 25 years, and i know i could save a lot of time and materials with PLCs, or PIC controllers but the time it takes to learn to program stips me dead. Just not enough time in a day. I am looking for something to use with the 20-30 custom systems I make annually and the price of add ons for the PLCs can be high.

Therefore this is a very good thing to be able to produce, as well as a pressure signal processor for the PLC if you have a circuit for that.

are the PT100 thermisters less than $5 ea? I get PT1000 for about $12 but in quantity it gets expensive.
Mike, I have at least 20 books about microcontrollers, from PIC's to GWBasics, to BX-20 processors, Basicstamp,...

All because I want to learn more about this but don't have the time. I followed courses for PIC, given by my friend. But we have to realize, this is really specialized work and if you want to do it on a certain level, you have to do it every day. There are so much tricks you have to know that it takes months before you reach a decent level.

If you want to start learning the basics of a microcontroller, then you should visit once the website of Parallax. You can download there freebooks explaining programming PIC's via some sort of Basic.It really starts at a low level and its written for kids in the technical schools in the age of 15 years.
I could realize after 1 week, each evening several hours making a thermostat which showed on an LCD actual temperature, my name , set temperature, DT,... I felt so happy that I understood finally how the controls of a multiline text- or graphic LCD works.
I have a small cupboard full of breadbords, led's ,IC's, Capacitors, resistors,..

Look once to my post of mid 2004 http://www.refrigeration-engineer.co...ighlight=stamp I haven't controlled the links.
There's a lot to find about microcontrollers.

Look also once at www.tri-plc.com (cheap and very reliable OEM PLC's, I have used some of them) and the very good and cheap product of www.unitronics.com, found in many machines, also Coca Cola uses these.

But, for 20 to 30 units/year, I think my friend can make something for you. Contact me once in PM and explain what you need. He already made a PCB for a small heatpump manufacturer/installer in The Netherlands for only 20 units/year. It reads several temperatures, pressures, a multiline text LCD, connected to the internet via IP, and freely programmable. It will cost in the range of 350 to 400 € (for the PCB)