Changing DMX512 footprint
 

Hello,

I have a driver with one ROOT DEVICE and 4 SUB DEVICES.
Every Sub_Device has his own DMX ADDRESS that can be changed with DMX_START_ADDRESS PID, but I need to change also DMX FOOTPRINT in 1:512 range.
How can I reach this goal? I can't find a natural way in RDM protocol.

Thank you

This is what personalities are for.

Get/Set DMX_PERSONALITY and Get DMX_PERSONALITY_DESCRIPTION

The Root device can have up to 255 personalities.
Each Sub-device can have up to 255 personalities.

Each personality can have a different DMX Footprint.

Yes, I know but the subdevices actually are 4 data distribution lines that need to be programmed with a DMX START ADDRESS and a FOOTPRINT as independent parameters from 1 to 512.
So FOOTPRINT here is actually treated as DMX START ADDRESS parameter, which conveniently is not included in DMX PERSONALITY in the RDM protocol.
In other words include footprint with DMX PERSONALITY is not the best choice and I would need another solution

Is this a multi-port "patching" splitter that allows each downstream port to have a different block of Null Startcode slots sent to it? For example, port 1 could be configured to take 100 slots of data starting from input slot 251, and it will retransmit it starting at slot 1?

The standard PIDs generally assume that universes are an inseparable block of data, so there aren't PIDs defined to slice universes in to multiple segments. RDMnet and E1.37 have the concept of a "Composite Universe", but managing composite universes is outside the scope of the standard.

It may be best to implement this with Manufacturer-specific PIDs.

I assume there will be other devices attached to the downstream ports? Will those devices only use NSC DMX, or will they also support RDM?

I would not recommend using Start Address for this, because some controllers will not allow you to patch fixtures on top of each other.