Mind you, I am talking about industrially hardened components. There may be some stuff on Amazon... that would be cheaper.
That's just it. The way I look at it, usually the homeowner grade stuff won't last long term. So, even tho it's cheaper, how many times do you want to buy it vs. buying the insustrial grade stuff once. Plus if you really want to monitor it on a daily basis from a distance, what do you do when it goes off line? What does it cost to go and fix it?
If things are a must, you go redundant.
The cost of fixing stuff. That's an "it depends" question.
Last spring I had to do a service call at a waste management company. Nothing was coming up on the screen for the incinerator control. This control system is Outside, and subject to Michigan weather.
After unlatching the door on the panel, I had to pry the damn thing open to see the gut's.
After getting online with the PLC and HMI, and a few quick tests, both are working fine, but it was a communication issue between both. Serial port on the PLC had issues.
They needed to get it going, so I popped a new processor in it. A OK!
Brought the old one back to the shop and checked it out. Corroded wire on the DB9 connector. A bit of solder fixed it.
Date code on this and when it was commissioned was 1984!!!
It ran without a skip for 29 years in a crappy environment!
HMI has a date code of 1987. That's when they got rid of the buttons.
I would call that a tad on the side of being reliable
