jjdekroon
Hello everybody,

First of all I'm new to this project and am very enthusiastic.
In my previous job I used to be "all-round service engineer" (electric, automation and mechanical engineer) in a dairy plant.
Here we used Siemens S5, S7-300's and S7-1200 PLC's all around the factory.
Nowaday's I'm a "Marine engineer" but am not really busy with PLC's anymore.
To keep my PLC skills a little fresh I was looking for a affordable way to keep my skills up-to-date and came across this interesting project.
I have some industrial equipment available to train on, but that requires me to use boards which support 24VDC in-/outputs which led me to the UniPi 1.1
Now I have a question regarding the UniPi 1.1 in relation to OpenPLC-Runtime.
If I want to expand the amount of in-/outputs of the UniPi, is this possible by using another UniPi as a modbus slave?
Also according to the UniPi website there is a possibility of expanding the amount of IO's over I2C protocol with the use of extension modules. Is this also supported by OpenPLC?
Hopefully somebody can shed some light on this for me.

Regards,

Jasper
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thiagoralves
jjdekroon wrote:

If I want to expand the amount of in-/outputs of the UniPi, is this possible by using another UniPi as a modbus slave?

Yes, that is totally possible. You will have to specify the characteristics of your slave modbus device (i.e. number of input registers, coils, etc) and use the Generic Modbus TCP for that.

jjdekroon wrote:

Also according to the UniPi website there is a possibility of expanding the amount of IO's over I2C protocol with the use of extension modules. Is this also supported by OpenPLC?

No, this feature is not supported on OpenPLC. However, if you have some C code experience, you can expand the current UniPi driver to support this by editing the hardware_layer.cpp file.
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jjdekroon
Thank you for your quick reply. Unfortunately I only have some basic C knowledge, but anyhow I can always try to help out. I'm thinking of ordering 2 UniPi boards so I have the hardware available then.
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thiagoralves
Instead of buying the basic UniPi 1.1, you might want to buy the Neuron PLCs, which are also compatible with OpenPLC. Their expansion capabilities are supported by OpenPLC
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jjdekroon
Thank you for the suggestion. It surely looks very interesting and is closest to regular PLC hardware. Also PIXTend v2 looks very interesting and on their website they advertise that they also provide support to the OpenPLC Project in the form of providing you with the nessasary code for hardware enablement is this correct? If yes that would give the PIXTend a moral advantage for me as I like to support hardware vendors which openly support opensource projects
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thiagoralves
Yes, that’s true. In fact they worked with me to write the current PiXtend driver for OpenPLC. Most of the code is theirs. The UniPi drivers, on the other hand, I wrote all by myself 
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jjdekroon
Okay, thank you for clarifying. That makes me more eager to buy a PIXtend instead of a UniPi to support a company which is actively contributing to opensource.
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epgodoy
Hello guys,
I was wondering if anyone of you has previous experience in using the OpenPLC with the UniPI (https://www.unipi.technology/unipi-1-1-p36?categoryId=7) and PiXtend (https://www.pixtend.de/shop/product_info.php?info=p56_pixtend-v2--s--extension-board.html) boards. We wanna buy a few boards for a project and wanna know which one is the best option (ease of use, reliability, robustness and etc).
The configurations and prices are quite similar, so it won´t be the major point of decision.
Another option would be the MegaIO-Industrial card (https://www.sequentmicrosystems.com/megaio-ind.html). I've contacted the company and they said it is going to be available online next month. This board is more interesting considering the IO capabilities and price. However it is not yet supported by OpenPLC. I've seen on another post that thiagoalves maybe could create a driver for it. But I do not know if he is actually planning to do that.
So, any help would be appreciated.
Thank you.
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thiagoralves
I would say go with the UniPi. My lab tests have shown that they are more reliable than PiXtend platform, although both are pretty good in general. However, if you're thinking about I/O expansion, maybe you can consider UniPi Neuron PLCs. They are also supported natively by OpenPLC and have nice expansion capabilities.

About the megaio, I still can write a driver if the vendor makes available the API to communicate with the expansion boards.
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epgodoy
I would say go with the UniPi.


Thiago do you know any place in the US selling the UniPi products?
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thiagoralves
I bought from their website and they delivered to me straight from Europe.
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