Custom ASCII serial over ethernet to AB PLC

[xetrov123]

If you don't need industrial ratings and temperature ranges, then you can use ESP32 module to convert serial to WIFI or Wired Ethernet. Less than $10/each.
Then it will be a simple Logix Socket code on the PLC side to poll these.
I believe ESP32 libraries have Modbus TCP implementation too.

Do you have an example of socket code implementing a custom ASCII serial protocol?

 

[Contr_Conn]

Do you have an example of socket code implementing a custom ASCII serial protocol?

The easiest one is to use the AOI from the technote QA6396, Access Levels: Everyone

 

[Contr_Conn]

Pylogix supports micropython now, so you could read/write without touching the PLC using those boards.

I will take a look. Thank you

 

[dmroeder]

I will take a look. Thank you

I sent you a PM

 

[drbitboy]

The serial protocol does not support multidrop.... I wish it did.

So there has to be a unique, addressable serial port and line to to each charger?

 

[JaxGTO]

You can get Point IO ASCII modules. Then write an AOI for the comms and call it for each charger. 1734-232ASC or the 1734-485ASC. You could have several of those in one Point IO bank, just have to be careful of the power draw.


I did this once for several label printers on a packaging line.

 

[xetrov123]

All great options!

The PointIO modules are less expensive, making that more interesting at scale (over a hundred chargers expected on campus)

Dmroeder, I am going to dive into your project. I do have some temperature constraints in some areas. I expect temps to reach 140° F in some sites.

I have a call in to Redlion to see what they recommend.

I'll post my progress and share what I can. Thanks! :site:

 

[dmroeder]

I didn't mean to hijack your thread. Contr_conn mentioned the ESP32, that sucked me right in.

 

[xetrov123]

I didn't mean to hijack your thread. Contr_conn mentioned the ESP32, that sucked me right in.

No worries! I am actually looking at your solution now. It seems like the temperature range may actually be appropriate. If you have any information or examples that are similar to mine, feel free to share.

 

[dmroeder]

No worries! I am actually looking at your solution now. It seems like the temperature range may actually be appropriate. If you have any information or examples that are similar to mine, feel free to share.

Do you think you'd be able to find a way to get data from the chargers using python? Pylogix would only help you get the data to the PLC once you have it from the charger.

 

[Ken Roach]

No skin in this game, just an EV and embedded stuff enthusiast.

The most reliable non-PLC device I've got in my shop or boat is a FriendlyElec NanoPi NEO LTS, running Node-Red. I set it up to monitor some stuff aboard about five years ago and send me SMS notifications, and I haven't touched it since. Power outages, brownouts, lightning storms, a blown inverter... it just keeps going.

TTL serial port, Ethernet, Linux so Python and Node-Red (thus PyLogix and the Node-Red CIP Ethernet nodes), aluminum case, 70C working temperature. Twenty bucks.

 

[dmroeder]

No skin in this game, just an EV and embedded stuff enthusiast.

The most reliable non-PLC device I've got in my shop or boat is a FriendlyElec NanoPi NEO LTS, running Node-Red. I set it up to monitor some stuff aboard about five years ago and send me SMS notifications, and I haven't touched it since. Power outages, brownouts, lightning storms, a blown inverter... it just keeps going.

TTL serial port, Ethernet, Linux so Python and Node-Red (thus PyLogix and the Node-Red CIP Ethernet nodes), aluminum case, 70C working temperature. Twenty bucks.

$20, dang, throwing that on my nerd list

 

[xetrov123]

Do you think you'd be able to find a way to get data from the chargers using python? Pylogix would only help you get the data to the PLC once you have it from the charger.

That's what I'm looking into right now. I'm guessing it has been done before. In reality, I need to figure out three serial reads and one serial write. If I figure it out once, it can't be that bad. Python isn't my strong suit but I'll have fun giving it a try.

 

[drbitboy]

That's what I'm looking into right now. I'm guessing it has been done before. In reality, I need to figure out three serial reads and one serial write. If I figure it out once, it can't be that bad. Python isn't my strong suit but I'll have fun giving it a try.

So you are putting a bespoke MCU or wifi/serial driver on each charger?

Writing Python code to do that should be straightforward once you get familiar with the language and figure out the module (I think it's called [serial]?).

 

[drbitboy]

The serial code for Python might look like this:

import serial

...

com = serial.Serial('COM3',38400,bytesize=8,stopbits=1, parity='N')

while True:

    ...

    sent = ...

    com.write(sent)

com.close()

...

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