MODBUS RTU
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Hello everyone
I would like to bring in the Omega 2 into the Industry. For that I was thinking about building a Modbus RTU dock. But I have some Problems. I'm not that familier with linux and I tried useing libmodbus, but running into the disk space problem does someone have a better Solution?
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It works perfect now, but it seems noone is interessted
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@Fabian-Nydegger Interested, sure! Just no immediate application for it
I'm using Omega2 in my building automation devices already, but no Modbus (yet).
What is your application?
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simply download https://pypi.python.org/pypi/MinimalModbus and opgk python, get any Rs485 converter https://www.sparkfun.com/products/9822 and test it. The dokumentation is very good also for beginners in modbus. I'll make a dock and case soon.
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I did not realize Modbus is RS485.
Does this mean that I already built a triple Modbus dock by accident by doing this?
(3 RS485 interfaces, Ethernet, 5..39V to 3.3V regulator, fitting into nice small Hammond 1591XXA case - designed to control Swiss Railway split-flap display modules)
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Yes if it's rs485 you just need to configurate the protocol, but remember most ModBus devices runs on 24V
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What omega did you use? If you implement this on Omega2 I’d be interested as everything I tried to get rs485/232 TTL support for the omega2 I ran out of space on the device...
I was however able to install python3-light, python3-pip and MinimalModbus on my omega2+ no problem. Omega2 doesn’t even have enough space to install both python3-light and python3-pip
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Is this RS485 adapter also 9bit aka multidrop capable ?
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@cory-callcott hi, if you read the documentation you'll find that there is a procedure to do overlay and use either a sd card or usb storage device. i use a 16GB flash drive and that gives me plenty of space.
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@Douglas-Kryder Thanks i'll look into it, I did read something about it but thought it was just for the 2+ model as it came with a sd card slot.
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@Gerhard-Bertelsmann Just using a cheap usb to rs232/ttl adaptor I think I got like 10 or so off ebay for like $10~15 a year or so ago. So far seems to work fine on omega2+.
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@cory-callcott
AFAIK none of the cheap USB2Serial devices is able to transfer 9bit. You can emulate it with mark/space parity but it takes a lot of time switching between the modes and hurts badly the effective transfer rate.
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Hello, I would be very interested in your omega to Modbus RTU as I would like to control an inverter which has Modbus from a PLC that works through the Omega onion.
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