Need a hint on DMX packet transmission update rate using Artnet + esp_dmx libraries

[knopserl]

Hi, sorry for this basic question but do I understand it right, that the values of all DMX channels need to be constantly transmitted in a certain frequency like 25 to 40Hz or FPS (refresh rate) and not just if any value of the channels has been changed? I'm using two libraries: one for Artnet and this one for sending the received Artnet values to one DMX universe. Artnet library used is this one: https://github.com/hideakitai/ArtNet (it supports Ethernet which I use and WiFi and also supports poll/response, discovery) In the loop, I also call artnet.parse which calls a callback, where I take the values from artnet and wrting/sending it to the DMX bus. I don't resend/refresh the values in the loop. So I don't to an cyclic update on the DMX bus if no value has changed in the main loop and I assume the esp_dmx lib does not either?. Is that DMX compliant or do I need to repeat sending out the current values in a frequency of 40Hz/FPS or does the esp_dmx library do it? Do I need to do it in the loop and what is the best way to do it with the esp_dmx lib? I have an ENTTEC USB device and I think this does the refresh with 40/44Hz. So I need to implement the same behavior as my control program (support USB and ArtNet) does not resend the DMX values.

Attached the source of the main sketch, the artnet and the DM part. I hope you understand my question and can provide me with a proper advise. BTW: I noticed that my Chineese Test DMX moving head device frequency goes back to a inital state and then gets the current setting agin after a few seconds (I think the artnet interval does that refresh and resend the values). This was the trigger for that question

ESP32-ETH-Artnet.zip

[k-dedman]

It depends on how you are connected to your DMX fixtures. If you are directly connecting the UART output to a RS485 transiever, you will need to call dmx_send or dmx_wait_sent in a loop. If you are using a 3rd party converter specifically for DMX, it may hold the last packet in memory and repeat it if it doesnt receive a new one in the required time. DMX fixtures require continuous packets or else they will turn off, the fixture im testing with turns off after ~1s of no input.

[knopserl]

It depends on how you are connected to your DMX fixtures. If you are directly connecting the UART output to a RS485 , you will need to call dmx_send or dmx_wait_sent in a loop. If you are using a 3rd party converter specifically for DMX, it may hold the last packet in memory and repeat it if it doesnt receive a new one in the required time. DMX fixtures require continuous packets or else they will turn off, the fixture im testing with turns off after ~1s of no input.

Thanks, that was the answer I was expecting. I directly connect my ESP32 sketch using esp_dmx via UART + RS485 (MAX485) to the fixtures and I have observed, that they turn to the default settings if no new DMX data are send by my sketch because no changes where made. So I need to resend the current (all) universe values constantly in the loop or are least with 25-45 FPS/Hz. I have tested the dmx_send in the loop, but it did only work if I combine it with dmx_send_num before the dmx_send. The is the in refresh loop (is that correct):
// refresh dmx_send_num(dmxPort, DMX_PACKET_SIZE); dmx_send(dmxPort);