DMXSimple Works on Some, Not on Others

Developed a DMX controller using an Arduino Nano and DMXSimple library, which can currently control 2 different manufacturer's lights. To simplify lighting code development, made a lighting simulator using a 30-channel DMX control board with RGB LED modules connected to each of the channels. This setup, mounted in a plastic box, will be a portable development platform, or so I'd planned.

Tested out the completed simulator's wiring using a commercial DMX controller and all 30 channels behave, lighting the LEDs as expected. When I connect my Arduino DMX controller however, which does properly light commercial DMX lights, the simulator's LEDs stay dark... not even a blink. I disconnect the Arduino DMX controller and plug in the commercial DMX controller and the LEDs light. The commercial lights work with the Arduino DMX controller and the commercial DMX controller, but the combination of the Arduino DMX controller and 30-channel DMX control board lighting simulator does not work.

Commercial DMX Controller + Commercial lights = Working Commercial DMX Controller + Lighting Simulator = Working Arduino DMX controller + Commercial lights = Working Arduino DMX controller + Lighting Simulator = NOT Working

Could DMXSimple's timing or levels be off just enough for the 30-channel DMX board not to work? THinking of trying the DMXSerial library which does not use the built-in Serial object but modifies the hardware registers directly.

How else can I troubleshoot this issue? Could compare output signals from Commercial DMX Controller and Arduino DMX controller on a scope but that will be tricky to see subtle timing differences.

THanks in advance!

When you say "To simplify lighting code development, made a lighting simulator using a 30-channel DMX control board with RGB LED modules connected to each of the channels." does this mean you made the test rig?

You have not posted your sketch and schematic so that makes diagnosis more difficult but from the way you describe, it sounds like the DMX reset and/or start mark timings are not suitable so the entire universe is ignored. If you made the test rig then maybe you can loosen the timings or hack DMXSimple to get better timings.

Another option might be worth testing with a different DMX library to see if that cures the problem as you will then know if the fault lies with DMXSimple or something else.

If your using that library to free up the Serial port then maybe consider using a different arduino like the Leonardo that has a native USB serial port and a UART port. I made a simple DMX tester using this method here.

... does this mean you made the test rig?

Yes, suppose you could call it that. This "simulator" box takes the place of several commercial DMX lights without the bulk and cabling. Just one DMX cable from controller to simulator.

You have not posted your sketch and schematic so that makes diagnosis more difficult...

THe sketch is quite lengthy but just uses DMXSimple commands to set lights to color and brightness. As for the schematic, uses the MAX485 chip from the Arduino to DMX connector, but as I look at it again, the pinouts from Arduino to MAX485 are different from some examples I'm seeing online, so perhaps the wiring isn't optimal and only works in certain situations.

I know the previous posts are older but since there is no solution posted I thought it may fit.

I ran into exactly the same problem with two new Par36 stage lights from a chinese manufacturer. They work fine with a commercial DMX controller but not with my arduino DMX controller. However my arduino controller works perfectly with a moving head and other stage lights.

Commercial DMX Controller + other lights = Working Commercial DMX Controller + new Chinese lights = Working Arduino DMX controller + other lights = Working Arduino DMX controller + new Chinese lights = NOT Working

I am using an arduino mega with a MAX485 breakout board.

I tried the follwing libraries: DMXSerial DMXSimple Conceptinetics_RDM

Each with the their corresponding example sketch for a controller. The result is the same.

The new Chinese lights have a DMX control LED that blinks when there is DMX signal detacted. It stays off. I switched the two lines of the DMX cable as I read in some older devices the signal is inverted. The result was that the DMX LED started blinking.The light responded to some values but not in the range of channels and functions it is intended. Also- the commercial controler works with standard signal so that cannot be the solution.

Anybody an idea what is going on? What is the commercial controller doing better?

Maybe your MAX485 is doing the same as mentioned in this thread where it appears some modules do not seem to release the A B lines correctly when not transmitting. Maybe this is especially important if your luminary supports RDM or that as the line is not released you cannot generate the Break needed at the start of a universe transmitting.

Ok, understand. I lack the abilities to measure the signals. So, to be on the safe side, I bought a MAX485 CPA from Digikey and I will be using your schematic of the little DMX Tester (very nice b.t.w.). I will post the results.