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I have a headlight connected to my rpi with dmx cable and a RS422 / RS485 Serial HAT shield (https://www.hwhardsoft.de/english/projects/rs485-shield/). According to the instructions it should be using the serial port over UART PL011. I have a Rpi 2 running raspbian. I don't manage to open this port in python and send commands to it. For example

ser = serial.Serial("/dev/serial0",9600)
ser.write("255")

does not work. With this I mean I have serial installed, the code runs, my light is listening (showing A001), but nothing happening to the light. I also found out about pySimpleDMX (https://github.com/c0z3n/pySimpleDMX) but then using

import pysimpledmx
mydmx = pysimpledmx.DMXConnection("/dev/serial0")
mydmx.setChannel(1, 255) # set DMX channel 1 to full
mydmx.render() render

Does not do anything and the connection with the dmx light is dropped. This board is meant for this kind of communication so I am sure it should be able to work, but I don't know how to do that. Many thanks for any advice

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Roughly translated, your question seems to be, "How do I write a Python program on the Raspberry Pi?" If that's a fair translation, it suggests you've not "done your homework"; i.e. you've not searched, read or tried to do this before asking your question.

If this is the case, I would suggest that you do that now... here's a place you might find useful as a first stop. After reading that, you should be able to write a simple Python program, and run it on your RPi. After that, try putting this in Google: how to write and run a python program on the raspberry pi; lots of help will follow.

If this is not the case, please edit your question so that it's more specific.

  • No this is definitely not my question, I know how to write and run python scripts.. I don't know how to send the right commands to the right ports to be able to control the light through dmx, I will clarify my question – crazjo Jun 15 '18 at 6:33
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@ crazjo: Hi, I'm nu to this topic also, so I can't really help you with your code itself from that point of view. However, you need to adjust the baudrate to 250k, since all DMX devices only work at this rate.

  • Hi and welcome to SE.RPi! Whilst you are indeed correct about the asynchronous serial data rate, your answer is a little terse. Could you provide a link (Wikipedia: DMX512: Protocol as an example? And how that compares to the Maximum Baudrate of UART in Raspberry Pi 3) and some additional information in your answer, as it is a little bit terse, and as such may be better suited as a comment. – Greenonline Aug 17 '18 at 21:38

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