Anyone with plc experience?

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I was looking for a ready made timer for a hydroponic system I'm
tinkering with and came across some el-cheapo PLCs on Amazon, and
figured this would work lots better than a timer that would need a lot
of additional circuitry to adapt.

The catch is that they mention a programming software that is from
Mitsubishi and costs $500+ .  After looking around I found some
cheaper alternatives but with more expensive hardware,  Further
searching led to an open-source software, but I'm ignorant of all the
standards and protocols they are mentioning.

Is there a newbie group for this sort of thing?  I see a lot of "home
automation," but they want cell-phone control plug-in stuff and it is
still costly.

I'm used to BASIC software for control applications, and most of the
PLCs use relay logic and I've used the "Automate" PLC in the 70's when
they were huge beasts - but easy to program with relay logic.  For the
hydro, I only need relay or OC outputs and switch inputs, nothing
fancy.  Initially I'm only controlling lights, hi/lo temperature
switch, hi/low nutrient switches, and switching a pump on and off.

Re: Anyone with plc experience? says...
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You may want to check out the Arduino.  You can get the basic modules  
from ebay for around $5 and some relay boards and many other things very  
cheep.  Usually from $ 5 to $ 20.  There is some programming software  
that is free to download off the internet.

They program up using what seems to be C++ or similar language.  
The boards remind me of a PLC as they have about 10 outputs of 0 or 5  
volts and a few other outputs  and about the same ammount of input pins.  

There is a book "Getting Started with Arduino" by Banzi and Shiloh  that  
goes through the programming and shows how to build an program a system  
to automatically water your garden.

You can go here to learn about them.

On the internet and youtube there are thousands of programs (which are  
called sketch).  


Re: Anyone with plc experience?
On Tue, 13 Aug 2019 10:48:58 -0400, Ralph Mowery

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That was Plan A - just program a pic microcontroller, and use the
ready-made clock timing module to keep it accurate, but I'm intrigued
by these Chinese PLCs that cost ~$15 with all relay outputs, and built
for industrial control environments, and super easy to program.

Re: Anyone with plc experience?
Automation Direct sells 69 dollar PLCs and  their software is free.

Re: Anyone with plc experience?
On 13/8/19 13:42, default wrote:
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Industrial Shields have PLCs based on  
Arduino. It seems that *finally* there are alternatives to the overly  
expensive traditional PLCs.

(I have no connection to industrialshields. I have just seen their  
products and liked the idea)


Re: Anyone with plc experience?

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I'm more interested in the <$20 PLCs with relay logic programming.

I can program a PIC to do what I want for ~$3.  But then I still need
relays etc to interface it.  The ones for $14-18 already have relay
outputs and program with an RS232 cable.

Since I have zero experience with Arduino, I want relay logic
programming not another hobby...

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