DMX over CAT5 vs DMX over CAT5 via IP

These days there are many means of distributing DMX instruction packets between devices appart from traditional 5 pin XLR cables. 5 pin has existed as an industry standard for many years, however with the changing demands of both the entertainment industry and complexity of technical theater, other solutions have emerged.

Nearly every new commercial or public construction project within the last twenty years comes prewired with three cables. Power, phone, and CAT5. The latter is of most interest. DMX instruction packet distribution over CAT5 offers several significant advantages, most notably cost and ease of use. Performing in an unorthodox space? Chances are CAT5 is already run through your venue!

Preexisting CAT5 cable can be utilized in two fassions.

Traditionally, early adopters of CAT5 simply used the cable as an inexpensive solution to long runs of 5 pin, doing a straight up electrical conversion. There is one quite glaring problem with the method. The R S-485 protocol that DMX runs on is not compatible with any TCP/IP hardware. In other words, DMX and standard ethernet based hardware are electrically incompatible, and connecting them will result in destruction of one or both pieces of hardware. The advantage of CAT5 to DMX cabling is no switching or routing hardware is needed, and the cable functions identically to a DMX run.

Since the late 1990's many companies have constructed their own TCP/IP based DMX conversion protocols. Since these protocols utilized the TCP/IP stack, the are 100% compatible with preexisting ethernet systems. One of the most widely accepted standards of TCP/IP DMX transmission is the ArtNet protocol. ArtNet can run through existing routing hardware (removing the costs of opto splitters) and distribute up to 256 individual DMX universes (256*512 =131,072 control channels) over one CAT5 cable! To make matters even better, ArtNet is a bidirectional connection, thus any ArtNet terminal can be reconfigured to work as a control module, allowing you to place your console literally anywhere with any ethernet jack.

Additionally, each lighting manufacturer maintains their own proprietary protocols for interface with their hardware. ETC, Strand, a, Pathway, MA, and Hog Ethernet protocols are entirely proprietary to the company. Often these protocols offers slight advantages over ArtNet, yet their lack of uniformity can make addition additional gear difficult.

Most hardware today (dimmer racks, intelligent fixtures, etc) come with or have options for ArtNet ethernet inputs, allowing these systems to be build inexpensively and efficiently. ArtNet nodes are available, which allow for conversion of ArtNet protocol to traditional 5pin DMX. When running an ethernet based system it is vital to stay on top of traffic over the network. It is highly recommended that you do not run 'internet' and lighting control protocol over the same wires, as it can increase network latency.

Now for the project. 30+ rooms over ethernet, cue stack for each room, one centralized time stream. Stay tuned!