DMX512 Cable
Digital Multi-plexing
DMX512 is a standard of communication. Technically, "DMX Cable" is 5-pin XLR cable, but is typically referred to as DMX cable to avoid confusion with 3-pin XLR cable that is used by sound. RJ-45 cable, also known as ethernet cable or CAT5/CAT6, can also be used.
Some fixtures, especially those on the lower budget end/DJ fixtures, may use 3-pin XLR for DMX, but this is prohibited by section 7.1.1 of the ANSI standard. Requiring fixtures to use 5-pin XLR cable prevents confusion with sound cables, especially those that may be carrying 48V phantom power that may damage the fixture. It also encourages the use of cable that meets the required construction standards as set by the ANSI standard, leading to prevention of signal degradation.
Some fixtures, especially those on the lower budget end/DJ fixtures, may use 3-pin XLR for DMX, but this is prohibited by section 7.1.1 of the ANSI standard. Requiring fixtures to use 5-pin XLR cable prevents confusion with sound cables, especially those that may be carrying 48V phantom power that may damage the fixture. It also encourages the use of cable that meets the required construction standards as set by the ANSI standard, leading to prevention of signal degradation.
For more about the DMX512-A Standard:
Connectors
Pin Layout:
Common Reference - Pin 1 - Data Link Common
Primary Data Link - Pin 2 - Data 1-
- Pin 3 - Data 1+
Secondary Data Link - Pin 4 - Data 2-
(Optional) - Pin 5 - Data 2+
Common Reference - Pin 1 - Data Link Common
Primary Data Link - Pin 2 - Data 1-
- Pin 3 - Data 1+
Secondary Data Link - Pin 4 - Data 2-
(Optional) - Pin 5 - Data 2+
Cabling
A single run of cable should not be longer than 1,300 feet long without a repeater.
No more than 32 individual devices should be on a single run. A splitter, often refered to as an opto-splitter, can be used to expand this number.
Each run of DMX should have a terminator at the end to absorb signal reflections.
No more than 32 individual devices should be on a single run. A splitter, often refered to as an opto-splitter, can be used to expand this number.
Each run of DMX should have a terminator at the end to absorb signal reflections.
DMX512 Universe
Each "out" on a DMX controller contains one "UNIVERSE." Each universe contains 512 addresses (previously referred to as channels). Each address contains parameters from 0-255, allowing for 16-bit control. Consoles will convert this to a percentage.
Fixtures will have a specific number of addresses needed for operation, often depending on the fixture personality. Standard dimmers use a single address. The Chauvet Ovation B-565FC LED fixtures that are in use at SU have 19 different control personalities that range in addresses from 3-31. The current personality selected uses 17 addresses per fixture. If one of the fixture's starting address is set to 101, it will take up addresses 101 thru 117. The last starting address that can be set is 496. If fixtures have overlapping addresses, one of the fixtures will get "incorrect" data from the console. Fixtures cannot be patched to overlap in the lighting console.
Fixtures will have a specific number of addresses needed for operation, often depending on the fixture personality. Standard dimmers use a single address. The Chauvet Ovation B-565FC LED fixtures that are in use at SU have 19 different control personalities that range in addresses from 3-31. The current personality selected uses 17 addresses per fixture. If one of the fixture's starting address is set to 101, it will take up addresses 101 thru 117. The last starting address that can be set is 496. If fixtures have overlapping addresses, one of the fixtures will get "incorrect" data from the console. Fixtures cannot be patched to overlap in the lighting console.