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4.3 Data
DMX 512 data is transmitted at 250 kiloHertz (kHz), meaning that 250,000 1’s and 0’s (at a maximum) can be
sent each second. Each bit is measured in 4 microsecond (µs) intervals. In order for the receiving device to
correctly interpret the data, it must be sent in a particular sequence. A single transmission (DMX Packet)
includes synchronizing elements and channel data for up to 512 channels (Figure 8).
Figure 8
The following table describes each element of the DMX Packet, including its line state, size and duration. An
idle DMX line will have a continuous HI (1) line state.
Table 2: DMX Packet
NOTE: At a minimum, a fully loaded DMX Packet (data for all 512 channels) will be around 5700 bits in
size. This means about 44 DMX Packets can be sent each second.
WARNING: DMX 512 has no error prevention, and is prohibited from use in life-safety applications such
as pyrotechnics or set/rigging motion control.
Element Description State Size Duration
Break The Break resets the line,
signaling a new DMX Packet. LO (0) 22-250
kbits
88 µs - 1 sec
Mark After
Break
(
MAB )
The MAB signals the receiver to
begin reading data. HI (1) 2-250 kbits 8 µs - 1 sec
Start Code
(
SC )
The SC is identical in size to
channel data, but always 0 in
value. Mixed 11 bits 44 µs
Mark Time
Between
Frames
(
MTBF )
The MTBF is used to space out
individual data bytes. HI (1) 0-250 kbits Up to 1 sec
Channel Data
(
CD )
The CD carries the 8-bit DMX
Value for each channel, plus one
start and two stop bits. Mixed 11 bits 44 µs
Mark Time
Between
Packets
(
MTBP )
The MTBP is used to space out
entire DMX Packets. HI (1) 0-250 kbits Up to 1 sec
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