14
Installation
Giotto Spot 400 CMY rel.1.00
2.0 -Construction of the signal cable
Giotto spot has a DMX 512 input fitted with standard 5-pin XLR connectors. Screened cables in compliance with EIA RS-485 spe-
cifications and the following characteristics must be used for connections:
- 2 conductors plus screen
- 120Ohm impedance
- low capacitance
- max. transmission rate 250kBaud.
Cable connections:
see illustration, taking care with the screen, which must be connected to Pin 1
A
TTENTION
:
the screened parts of the cable (sleeve) must NEVER be connected to the system's earth, as this
would cause faulty fixture and controller operation.
Example of connection of the DMX line
To avoid the risk of faulty operation, follow these indications:
Maximum cable length:
500 metres
Max. N° of fixtures connected:
32
Cable runs:
Avoid running cables alongside power supply lines.
Termination:
A 120Ohm resistor between Pins 2 and 3 on the last fixture.
2.1- Construction of the DMX termination
The termination avoids the risk of DMX 512 signals being reflected back along the cable when they reaches the end of the line:
under certain conditions and with certain cable lengths, this could cause them to cancel the original signals.
The termination is prepared by soldering a 120Ohm 1/4 W resistor between pins 2 and 3 of the 5-pin male XLR connector (see
diagram).
1
2
3
4
5
120
Ω
DMX Termination
DMX controller
DMX Line
pan
tilt
1
2
3
4
5
COMMON
DMX-
DMX+
