Remote Device Management (RDM) is an addition to the DMX512 control protocol for stage lighting equipment, introduced in 2006.
RDM revises the DMX512 standard to include bidirectional communication, and introduces additional options for the configuration of fixtures over the DMX512 network.
RDM is backwards compatible with existing DMX512 devices, and requires few changes to the physical cabling of DMX512 networks.
The RDM standard was developed by the Entertainment Services and Technology Association, and is maintained as ANSI E1.20.
[3] RDM serves multiple main functions: identification, status reporting, and configuration.
Intelligent lighting fixtures often have multiple control modes and other settings, which can also be configured over RDM with the proper software support.
Protocols that carry DMX signal over IP networks, such as Streaming ACN and Art-Net, have their own implementations of remote control which are backwards compatible with RDM.
To ensure this lack of collisions, while making possible implementation on different platforms, there are times when all line drivers are required to be disabled.
The Line Biasing network shall maintain this bias when the data link is loaded with the equivalent of 32 unit loads and common mode voltage is varied over the range of +7 volts to -7 volts DC.” The standard does not require any particular circuit for providing the basis and termination; however, the simplest method is often a passive pull apart network.
Whatever method is used must be tested with the chosen driver chip to see that the design combination still meets the requirement of E1.20.
The RDM standard addresses this problem by ensuring that in all cases (except discovery) only one device is authorized to be transmitting at any given time.
All RDM devices have a unique identifier (UID) that consists of a manufacturer ID and serial number.
RDM communication can be broken down into three types: Discovery is the only situation in which data collisions can occur assuming all connected devices behave correctly.
Unicast communication is the only way in which data can be retrieved from a fixture (other than its UID which can be obtained using the discovery mechanism mentioned above).
If the device does not respond within a given period of time, the controller can assume communication has failed, and may retry.
To quickly send instructions to multiple fixtures, RDM allows for broadcast communication.
As more than one device might be receiving the message, responses are not permitted in broadcast communication except during the Discovery process.