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Crestron MPS-300 Multimedia Presentation System 300
Calculate Power
CAUTION: Use only Crestron power supplies for Crestron equipment. Failure to
do so could cause equipment damage or void the Crestron warranty.
CAUTION: Provide sufficient power to the system. Insufficient power can lead to
unpredictable results or damage to the equipment. Please use the Crestron Power
Calculator to help calculate how much power is needed for the system
(
http://www.crestron.com/calculators).
When calculating the length of wire for a particular Cresnet run, the wire gauge and
the Cresnet power usage of each network unit to be connected must be taken into
consideration. Use Crestron Certified Wire only. If Cresnet units are to be daisy-
chained on the run, the Cresnet power usage of each network unit to be daisy-
chained must be added together to determine the Cresnet power usage of the entire
chain. If the unit is home-run from a Crestron system power supply network port, the
Cresnet power usage of that unit is the Cresnet power usage of the entire run. The
wire gauge and the Cresnet power usage of the run should be used in the following
equation to calculate the cable length value on the equation’s left side.
Cable Length Equation
L = Length of run (or chain) in feet
R = 6 Ohms (Crestron Certified Wire: 18 AWG (0.75 MM ))
or 1.6 Ohms (Cresnet HP: 12 AWG (4 MM ))
P = Cresnet power usage of entire run (or chain)
2
2
L <
40,000
R x P
Where:
Make sure the cable length value is less than the value calculated on the right side of
the equation. For example, a Cresnet run using 18 AWG Crestron Certified Wire and
drawing 20 watts should not have a length of run more than 333 feet. If Cresnet HP
is used for the same run, its length could extend to 1250 feet.
NOTE: All Crestron certified Cresnet wiring must consist of two twisted pairs. One
twisted pair is the +24V conductor and the GND conductor and the other twisted
pair is the Y conductor and the Z conductor.
Strip and Tin Wire
When daisy-chaining Cresnet units, strip the ends of the wires carefully to avoid
nicking the conductors. Twist together the ends of the wires that share a pin on the
network connector and tin the twisted connection. Apply solder only to the ends of
the twisted wires. Avoid tinning too far up the wires or the end becomes brittle.
Insert the tinned connection into the Cresnet connector and tighten the retaining
screw. Repeat the procedure for the other three conductors.
Add Hubs
Use of a Cresnet Hub/Repeater (CNXHUB) is advised whenever the number of
Cresnet devices on a network exceeds 20 or when the combined total length of
Cresnet cable exceeds 3000 feet (914 meters).
Reference Documents
The latest version of all documents mentioned within the guide can be obtained from
the Crestron website (
http://www.crestron.com/manuals). This link will provide a list
of product manuals arranged in alphabetical order by model number.
Operations Guide – DOC. 6529B Multimedia Presentation System 300: MPS-300 • 87