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DMX512 Discussion Discussion and questions relating to DMX512-A and DMX512/1990.

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Old November 21st, 2017   #1
Nelly
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Default Refresh rate from DMX controller

Hello there,

I have bought an Arduino board and a DMX shield to get the DMX functionalities to the Arduino. I have tried to connect the DMX shield to a LED driver that runs DMX but it seems like the LED driver doesn't get any DMX signal at all. Then I tried to connect the DMX shield to a Lightcorder (a device that can read the DMX signal). The lightcorder reads the DMX signal without any problem at all which tells me that the problem is between the shield and the LED driver.

I have also tried to measure a DMX signal (The LED driver can see this signal) send from another DMX controller to the LED driver and the only difference between the two signals that I know of is the refresh rate. The DMX shield is transmitting with a refresh rate of 19-20 Hz and the other equipment is transmitting with 40-41 Hz. Can this be the problem? Is it possible that the LED driver is made in a way that it can't receive DMX with a refresh rate that is 20 Hz?

Best regards
Christian
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Old November 21st, 2017   #2
ericthegeek
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The refresh rate ("Hz") tells you basically nothing. What matters is the timing of the individual elements within the DMX packet. We can't really answer your question without having a lot more details about the setup. You'll likely need an Oscilloscope or DMX tester to get much further.
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Old November 22nd, 2017   #3
Nelly
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Hello again,

Thank you for the answer. I'm sorry for the lack of information but I'm quite new to DMX so I'm not 100 % sure about the information you want me to deliver. Can you please tell and I will find the information for you?

The Lightcorder is a kind of DMX tester as far as I know. It reads the signal and tells me the different DMX values on the different channels.

Best regards
Christian
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Old November 22nd, 2017   #4
ericthegeek
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If you want to troubleshoot it, you'll need to look closely at the signal timing (min/max for break length, MAB length, byte spacing, etc.).

There are a lot of poorly implemented DMX devices out there. You may want to try a different LED driver.
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Old November 29th, 2017   #5
Nelly
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Okay and thank you for the answer!

I know for sure that the LED driver is of high quality. I have tried 3 different LED driver models from EldoLED and one LED driver from KKDC. The LED driver from KKDC make the LED flicker, when it receives the DMX signal. Does that tell you anything?

I will try to get an oscilloscop to check out the timing of the signal.

Best regards
Christian
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