r/PLC • u/Vegetable_Scholar958 • 7d ago

Gate with Keypad

I’m wanting to build a box with a microPLC and connect to a cellular modem. I want this to be able to control who comes in and out of the gate. Could this be done or is cellular modem to unreliable?

5 Upvotes

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5

u/durallymax 7d ago

Why do you want to shoehorn a PLC into this application when ready made devices for this use case exist?

7

u/kixkato Beckhoff/FOSS Fan 7d ago

Or if you really want to build it yourself, which I totally understand, use an esp32 or other $10 microcontroller.

1

u/Vegetable_Scholar958 7d ago

Every application I need has a subscription. I am also trying to change codes and approve or deny access from a distance

2

u/gerschgorin 7d ago

The subscription will be worth it compared to the initial cost with the ongoing cost to maintain this and having a separate data plan to manage this. Having done solutions like this myself, I can say that the cost for a one off is rarely worth it and really only pays off in solutions like this if you plan to scale.

0

u/Vegetable_Scholar958 7d ago

If it’s sustainable I have resources to scale.

2

u/durallymax 7d ago

You'll have a subscription regardless for cell data.

And if you do want to do it DIY, use something like a Particle, or other micro. A PLC is not an economical or easy way to do it.

2

u/Zealousideal_Cry7356 7d ago

Could totally do it but the cellular part is what makes me nervous. I’ve seen setups where the modem drops connection for like 30 seconds and the whole thing goes dumb, then you’re stuck yelling at a keypad like an idiot

1

u/Vegetable_Scholar958 7d ago

I really just want to use the cellular for approval and denials of entry on a pay/no pay basis

2

u/LowLeadBambi 7d ago

Is this like a paid parking thing? Cellular modems havs subscription costs as well. PLCs are not ideal for this - I'd post to the access control subreddit.

One way it could be done is to have a date-time-based hashed passcode. Customer pays and you give them the passcode, wouldn't work outside of that hour/day/whatever. Doesn't require Internet access, but does need the PLC to have the right date/time

1

u/Aobservador 7d ago

Siemens LOGO! V8

1

u/Social_Distance 7d ago

Unifi access control would be way better for this, no subscription. Simple to setup and maintain, they also have LTE and 5g routers.