System information

Artistic Licence Engineering Ltd. Micro-Scope 3a Manual

21 / 78

TIMING

MODE

Detail mode provides four further pieces of information about the

DMX signal.

The Period "P" is the time between received Breaks on the DMX512

signal. The reciprocal (that is

the ‘1/x’ button on your

calculator) of this number

gives the refresh rate.

The second number is the Break time "Bk". This is the length of the

synchronising code used to restart a new DMX frame. The

specification requires this value to be 88uS or greater. If this is

not the case, the timing error icon "T" will be displayed in the main

receive window.

The third number "C" represents the number of dimmer channels

received in the last DMX packet. This number should be constant,

although the value may be less than 512, depending on the type of

console used.

The fourth number is the Mark after Break time "MaB". This is the

delay between the end of a Break and transmission of the start

code. The specification requires a MaB of 4us or greater. If this is

not the case, the timing error icon "T" will be displayed in the main

receive window. (The MaB limit was increased to 8uS in the

DMX512 1990 Revision).

The DMX512 timing analyser in menu 1 has been improved and now

displays data specific to the selected start code (menu 4). That is:

 ‘P’ This is the period or time between DMX512 frames. If the

start code (menu 4) is set to ‘don’t care’ this will display the

time between all consecutive frames. In networks containing

RDM, it can be difficult to interpret as the packet lengths are

so different. When the start code is set to a specific value,

the time period displayed will be a measure of the time

between DMX512 breaks of consecutive packets with that start

code. The result is a more accurate view of packet timing and

bandwidth use.

 ‘Bk’ This is the break time. If the start code (menu 4) is set to

‘don’t care’ this will display the break time of all frames. It

can be useful to view the break time of packets with a

specific start code, which is achieved by setting the start code

in menu 4.