DMX Packet Info

[zman]

Does anyone know if the iDMX sends variable length or full length DMX packet info?

Thanks,

Mark

[dmoore]

zman wrote:

Does anyone know if the iDMX sends variable length or full length DMX packet info?

Thanks,

Mark

In testing it with the Tiger 120 board, Phil (who wrote the firmware for that board) indicated to me that some of the issues I was seeing was a result of a partial DMX packet. I didn't do any additional testing nor do I have a decoder for the stream to confirm that.

[LightORamaDan]

The iDMX sends out two packet sizes 256 and 512 ... The default is to send 256 byte packets. Two conditions will cause it to switch to 512 packets. If a LOR command is received for a DMx address higher than 256 or a DMX packet is received (on the DMX input port) with a packet size larger than 256.

There were two reasons we went with the 256. Originally the iDMX only supported 256 addresses (From LOR) so unless there was a DMX input there was no need for packets sizes larger than 256. Secondly, internally when effects such as a fade are calculated the intensity is updated 120 times per second. By using a 256 byte packet we could increase the refresh rate and take better advantage of the effects being generated.

All DMX equipment is supposed to handle packets of any length. If there is ever an issue with the 256 byte packets you can simply add a channel to the iDMX for an address higher than 256. This will force the iDMX to 512 byte Packets.

Dan

[zman]

Dan,

Thanks for that tid bit, that was golden and may help me out tremendously this year. In you testing of the 512 packets, was there any performance issues? Especially using ELLs?

Looks like my mixed universe LOR/DIY is getting all the DIY stuff re-based addressed to 257.

Mark

[LightORamaDan]

zman wrote:

Dan,

Thanks for that tid bit, that was golden and may help me out tremendously this year. In you testing of the 512 packets, was there any performance issues? Especially using ELLs?

Looks like my mixed universe LOR/DIY is getting all the DIY stuff re-based addressed to 257.

Mark

No real performance problems. With 512 packets you get about 40 frames per second which is pretty fast and is what many DMX controllers generate.

You do not need to re-base your DIY stuff. You can just add a channel with address 257 (or 512 for that matter) in it. Give it a name like "Enable 512" so you remember why it is there. There doesn't need to be a anything actually listening to that address. Then you can keep your stuff addressed as it is.

Dan

[zman]

Very cool Thanks again Dan.