R2-Net Protocol

Device connection diagram for the R2-Net bus

Each device basically has four wires, two for power and two for R2-Net communication. It is possible that depending on the characteristics of the device there are more connections or variants.

What is it and … what format does a telegram have?

The telegram is about the sending of a data number by the R2-Net bus. The standard format of a telegram is as follows:

  • Header – Command – Unit – All – Data – End of frame

Where:

  • Header: it is a frame start byte, it is always the character “@” -> ascii 64.
  • Command: is a byte that contains the command to perform.
  • Unit: is the number of the device to which the telegram is addressed (recipient).
  • All: is a priority byte to Unit. What it does is that all the devices that have implemented the command act with the content and data of the telegram.
  • Data: byte with the value of what is transmitted.
  • End of frame: byte indicating the end of the frame, always character CR -> ascii 13.

This is the color command of the R2-Net holo-projectors, in total 9 bytes:

  • Header – Command – Unit – All – Red – Green – Blue – White – End of frame

Where:

  • Header: character “@” -> ascii 64
  • Command: character “L” -> ascii 76
  • Unit: recipient -> 1
  • All: Byte all -> 0
  • Red: byte with the value of the color red (0-255)
  • Green: byte with the value of green color (0-255)
  • Blue: byte with the value of the color blue (0-255)
  • White: byte with the value of white color (0-255)
  • End of frame: byte indicating the end of the frame -> ascii 13.

The telegram to set holo-projector 2 to 100% Blue is as follows:

  • @ L 2 0 0 0 255 0 13

The “all” byte is especially important when we want all the devices of the same command to be affected, if for example we want the three holo-projectors to turn blue, it will suffice to send the same telegram setting the byte to 1 “all “…

It looks like this:

  • @ L 2 1 0 0 255 0 13

For this purpose, all the devices on the bus that have the “L” command will be affected by this telegram.