several times a year. These allow RDM manufacturers to interface gear from other manufacturers with their own. This has led to greater inter-operability. For RDM responders there is an open source suite of Automated Responder Tests. Compatibility with new technologies RDM has been designed with the traditional DMX-512 serial interface in mind. It relies heavily on a few assumptions that could affect its compatibility with other lighting technologies. RDM relies on there being only one controller on a single line, to manage its collision prevention. A number of products exist to allow multiple DMX streams from multiple controllers being merged into one DMX stream. While this is fairly trivial in a unidirectional environment, it becomes much more complex when RDM is involved, as it can quickly get very difficult to route the RDM responses from devices back to the correct controller. RDM relies on devices replying within a given time-frame of a response completing. If a device does not begin responding in the correct time-frame, the controller will most likely retry its request or give up. In a DMX-only environment this is not a problem as the delay between the device and the controller is likely to be very, very short. If the DMX is being routed down an intermediary medium (such as down a TCP/IP (Ethernet) network or wireless interface) then this can cause some problems. In general, if the manufacturer has control over the intermediary interface (as they do for protocols such as wireless DMX), it is possible to forward on the RDM responses as they are being received, along with a proxy system for the discovery process to provide the illusion of the RDM communication occurring as normal. If the manufacturer does not have control over the implementation of the intermediary interface (such as when using an Ethernet network) then it is virtually impossible to send RDM messages back to a DMX-based RDM controller. It is possible, however, to maintain RDM communication with DMX-based devices and an Ethernet-based controller. Since lighting controllers are already rapidly heading towards being entirely Ethernet-based, this is the form DMX/RDM devices are most likely going to be seen in the future. With both RDM and DMX communication originating on the Ethernet medium, being converted through an Ethernet-to-DMX output device, and then proceeding to DMX-based devices. See also Dimmer Lighting control console Lighting control system External links Specifications ANSI E1.20 RDM-Remote Device Management