E1.20 RDM (Remote Device Management) Protocol Forums - View Single Post - Enttec RDM USB Pro not decoding get response

dtewksbury · December 7th, 2013

Hello everyone, this is my first post here.

I am implementing RDM for our new LED fixture range (to be released soon I hope). I have not implemented RDM before, and so this is very early days for me. I am using an Enttec RDM USB PRO as the controller device. I have written a custom application in windows to control it and that seems to work ok.

However, I am having a problem with it not decoding the GET_COMMAND_RESPONSE packet. My micro in the fixture is correctly decoding the GET_COMMAND, testing the checksum, manufacturer ID etc, and sending the appropriate response. I have checked the return packet as best I can with the DSO, and all values seem to be correct. I have very accurate timing control in the micro (PIC24 series @ 40MIPS). I am using a timer driven state machine and set my timing accuracy for all DMX generation to increments of 200nS, which easily allows me to adhere to the specification outlined in the ANSI E1.20 document. All timing seems correct to me, but he RDM USB PRO will not decode and send back any packets to my software.

I have confirmed that I can get packets from it before while I was developing. But now that I have all the RDM data filled in correctly I don't get anything.

Am I missing something? Does anyone know what the rules are for it to decode a packet and send it back? I cannot find any documentation that outlines how clever this device is, like is it aware of what the last request was that it transmitted, and therefore what it expects to decode next? I would have thought that it would decode anything and leave it up to the software to determine the validity of what was received by the device.

Sorry for the long explanation, I can supply further details if required by anybody that has had any experience with this device.

Thank you,

Daryl.

December 7th, 2013	#1
dtewksbury Junior Member Join Date: Nov 2011 Location: Phuket, Thailand Posts: 7	Enttec RDM USB Pro not decoding get response Hello everyone, this is my first post here. I am implementing RDM for our new LED fixture range (to be released soon I hope). I have not implemented RDM before, and so this is very early days for me. I am using an Enttec RDM USB PRO as the controller device. I have written a custom application in windows to control it and that seems to work ok. However, I am having a problem with it not decoding the GET_COMMAND_RESPONSE packet. My micro in the fixture is correctly decoding the GET_COMMAND, testing the checksum, manufacturer ID etc, and sending the appropriate response. I have checked the return packet as best I can with the DSO, and all values seem to be correct. I have very accurate timing control in the micro (PIC24 series @ 40MIPS). I am using a timer driven state machine and set my timing accuracy for all DMX generation to increments of 200nS, which easily allows me to adhere to the specification outlined in the ANSI E1.20 document. All timing seems correct to me, but he RDM USB PRO will not decode and send back any packets to my software. I have confirmed that I can get packets from it before while I was developing. But now that I have all the RDM data filled in correctly I don't get anything. Am I missing something? Does anyone know what the rules are for it to decode a packet and send it back? I cannot find any documentation that outlines how clever this device is, like is it aware of what the last request was that it transmitted, and therefore what it expects to decode next? I would have thought that it would decode anything and leave it up to the software to determine the validity of what was received by the device. Sorry for the long explanation, I can supply further details if required by anybody that has had any experience with this device. Thank you, Daryl.