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Comment by anfractuosity | Hacker News Reader

I was curious about using a PLC for brewing, to have a little play with ladder logic etc. and had a look at the CLICK PLCs which have for example an RTD module ( https://www.automationdirect.com/adc/shopping/catalog/progra... ) however even that module itself is $165. Curious if anyone has any recommendations for cheaper PLCs that support 3+ wire PT100 probes.

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In general, new industrial equipment is priced for businesses who spend so much money on other expenses that they don’t really care if a PLC is $50 or $500 as long as it keeps their $50,000/day line running.

For home use, you can try eBay, but I’ve had better experiences with my local industrial surplus shop. They pretty universally (IME) have friendly staff who like talking shop, will point you toward the right equipment, and are pennies on the dollar compared to buying new.

Yeah that's a good point about buying used, I had a little look on ebay a while ago. Will try searching for industrial surplus shops like you say though.

Honestly, that’s dirt cheap for a PLC. I’d say that you should have a look on Craigslist or eBay, but you probably won’t find anything much cheaper. Also, a lot of PLCs are “cheaper” because they have relatively expensive software packages required for programming them.

You’d probably do much better with a RPi and a RTD module (1-wire, i2c, etc). You wouldn’t get the ladder logic, but you could use node-red. Heck, there might even be a ladder logic based program for the RPi. I wouldn’t be surprised.

Usually BH is the cheaper more capable solution. Add a el3204 if its not already build into the core you buy and voila.

cheaper than that is hard. One around that is the Revolution Pi, based on Raspberry Pi, but industrial grade.

Cheers, that looks pretty interesting.

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