What is RDM?

Remote Device Management is a protocol that sits on top of the DMX data standard for lighting control. DMX is a unidirectional protocol which means that the data flows in one direction – from the control desk to the lights.

With the addition of RDM, the DMX512 system becomes a bi-directional (half-duplex) system. The controller is able to send out a question to devices on the wire, which can then respond with an answer.

The messages within the protocol cover all the everyday tasks a lighting system manager incurs – setting DMX addresses, modes and other configuration tasks, plus monitoring sensors, usage, status messages and fault finding.

Think of an RDM transaction as a conversation – the lighting desk says ‘tell me your DMX address’ and the fixture responds with ‘my address is 32’. This is known as a GET command. Next the controller can send a SET command, such as ‘set your DMX address to 65’, and the fixture can respond to acknowledge this change. In this way, through GET and SET commands and responses, the RDM protocol allows a control desk to modify and monitor the DMX system in ways never possible before.

So, sounds great? How do I turn it on?

Well, there are a few things you need to know first:

  • DMX512 products do not inherently support RDM
  • RDM ‘ready’ products have been shipping for many years
  • Only RDM ‘enabled’ products will actually use the RDM standard – these are not as common as RDM ‘ready’ products, so check the specification sheet of your equipment first. (Or check out our Products list).
  • The RDM standard requires only a limited subset of the functions available within RDM. This means that some equipment that ‘supports’ RDM may not support the features you want – always check with the manufacturer before assuming that something will work.

Assuming your equipment has RDM fully implemented, you’ll need an RDM controller. There are a wide range of controllers available from simple handheld controllers, which can detect devices and modify their settings, through full lighting control desks which integrate the RDM functionality into their control interface. The RDM functionality varies by product, but there will always be an interface to ‘discover’ the RDM devices.