Installing The Electronics Housing - RayTek MARATHON FA Operating Instructions Manual

5.4 Installing the Electronics Housing
The distance between the electronics housing and a computer (via RS485 cable) can be up to 1200 m
(4000 feet). This allows ample distance from the harsh environment where the sensing head is
mounted to a control room or pulpit where the computer is located.
For reliable performance it is recommended that the power supply be no more than
60 m (200 feet) away!
Following you can see installation examples shown with two representative cable types. A 4‐wire
cable is used to wire the 24 VDC power supply and one output of the electronics housing. A coated
12‐wire cable is used to wire all inputs and outputs of the electronics housing.
Sometimes in cable both sets of twisted‐pair wires have drain wires inside their insulation. These
drain wires must be assembled and connected to the terminal labeled SHIELD (bare). Also connect the
earth ground to the SHIELD (bare) terminal. The following figure shows how to configure the drain
wires of both 4‐ and 12‐wire cables before connecting to the sensor and RS485/RS232 converter.
Attach to SHIELD
in electronics housing
To electronics housing
Attach to SHIELD
in electronics housing
To electronics housing
The complete wiring must have only one common earth ground point!
Cables can be run to the electronics enclosure through conduit or fastened using the a compression
fitting. Once you run the cable into the enclosure, attach the color‐coded bare wires to the terminals.
Use the following figure (or diagram on underside of lid) as a wiring guide. Note that the terminal
blocks in the electronics enclosure can be "popped" out for easy wire connections.
Marathon Series FA/FR
Twist braided shield and two drain wires from
the two twisted pairs together
12-wire cable
4-wire cable
Figure 14: Configuring the Sensor Cable
Installation
to power supply,
to RS232/485 converter,
other inputs/outputs
Earth Ground
to power supply,
0/4 – 20 mA current output
Earth Ground
e.g.
e.g.
19