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Unique Dimmer Numbers (UD#s)
Unique Dimmer Numbers identify each dimmer in a Sensor system
individually (up to 8192 dimmers per system). UD#s are assigned by the
Control Electronics Module (CEM) according to rack address and dimmer
position.
The lowest UD# for each rack is the First Unique Dimmer Number (shown on
the CEM status display as 1st UD#:). By default, the dimmer in a rack’s top
slot is assigned the 1st UD#.
Balanced racks
distribute Unique
Dimmer Numbers in
each phase
Phase A
Phase B
Phase C
Dimmer numbers
(Balanced rack)
Start
(DMX 101)
1
2
7
8
13
14
19
20
3
4
9
10
15
16
21
22
5
6
11
12
17
18
23
24
1
2
7
8
13
14
19
20
3
4
9
10
15
16
21
22
5
6
11
12
17
18
23
24
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
Sequenced racks have
dimmers numbered
sequentially from top to
bottom
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
D20AF
Figure 4: Balanced and sequenced dimmer numbering
In “balanced” racks, the numbers are distributed on each electrical phase. In
“sequenced” racks, dimmers are numbered sequentially from top to bottom.
When dimmers are balanced, DMX channels are still applied in order of the
UD#. This causes DMX channels assignments to skip down through the
dimmers in the rack.
In systems with multiple dimmer racks, each rack is assigned an ETCLink
address. This rack address determines the UD#s assigned to dimmers in each
rack. For example, in a system with three 24-dimmer racks, rack number one
would hold dimmers 1 through 24, rack two would have dimmers 25 through
48 and rack three would have dimmers 49 through 72.
Rack addresses and dimmer distribution are set at the factory before racks are
shipped and dimmer slots are numbered with one or two UD# labels.
Figure 5: Applying DMX in a
balanced dimmer rack
8
Electronic Theatre Controls, Inc.