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Old November 17th, 2020   #1
Junior Member
Join Date: Nov 2020
Posts: 3
Default Discovery response format

I am having trouble with the Discovery Response signal and am unsure on how to fix it.

Current setup:
Iím sending an RDM Discovery signal with a DMXcat (controller) to a PSoC 4 controller (responder) with a rs485 shield to receive the data. The rs485 shield is in TX_CTRL mode, this would mean that the switch between TX and RX mode is made automatically by the shield. I am correctly receiving the Discovery signal on the responder but seem unable to return a response. I hardcoded the response in an array according to the standard in the E1.20 sheet. It consists of 8 Preamble bytes, 1 preamble separator byte, 12 EUID bytes and 4 encoded checksum bytes.

The Problem:
After sending the response I am unable to see any feedback as to what happened to this response. I am unsure what is causing the response to seemingly get lost. I have a couple of ideas as to what could be the issue but I donít know how Iíd be able to test if these ideas are true.

Possible solutions:
From what I can tell, the issue could be caused by a few things:
  • It could be that the response Iím sending is incomplete, but as far as I can tell from the E1.20 standard, this is not the case.
  • Another reason could be that I am incorrectly sending the array or it shouldnít be an array in the first place. Itís currently in an array of HEX values.
  • I do also still have my suspicions that the rs485 might not be correctly sending the data in automatic mode.
I think I might be able to properly solve this with a RDM sniffer but I am unable to find a proper one so far. The best one I found is the Enttecc RDM USB PRO (PN 70530), but it doesnít seem to be available anymore.

The main question:
The main questions are mostly centered on what could be an issue with sending the response and what is a good RDM sniffer.

Thanks in advance.
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