Raypak Y-200 - Manual (Page 9)

9
Communication (RS485) Wiring
Required for Optional Slave
Unit(s)
Y-304 Slave Cable Installation from
System Control module
• Y-304 slave cable or equivalent shielded commu-
nications cable (Belden #9842, Belden #8132 or
Alpha 3492C) must be used. Maximum cable
length 100 ft. Correct polarity must be observed.
Make use of wire color coding to ensure polarity.
• The shielding [foil wrapper-bare wire (drain)]
MUST be grounded. Grounding is done at the
Master Y-200 Control only. DO NOT ground the
shield at the slave unit end of the cable.
• Note: Equivalent shielded cable must be suitable
for RS485 communication applications; must have
100-140 ohm impedance and less than 30 pico-
farad per foot capacitance.
• Must be installed in conduit that does not contain
any other wiring.
• Port J18 (see Fig. 4) is used for the interconnec-
tion between the master controller and slave units.
• Master/Slave interconnection should be wired
from Master to Slave #1, Slave #1 to Slave #2,
Slave #2 to Slave #3, and Slave #3 to Slave #4.
Air Temperature Sensor
Installation
• Locate the sensor on the coldest side of building,
usually the north side.
• Install the sensor in a shaded area, out of direct
sunlight.
• Locate no higher than 2/3 way up the side of the
building, or between the 2nd and 3rd floor if the
building is more than 3 stories tall.
• Do not locate under an overhang, near wall cor-
ners, near drafts from stacks, air moving devices,
windows, doors, or balconies.
• Shielded twisted pair (18 AWG) must be used for
sensor connections. Polarity must be observed.
Cable length shall not exceed 300 feet, and the
shielding must be grounded.
• Grounding is done at the Master Y-200 control
ONLY. Do Not ground the Slave units or
Temperature Sensor enclosure.
• Must be installed with properly-sized conduit that
contains no other wiring.
• The outdoor air temperature and water tempera-
ture sensor are identical and interchangeable.
Fig. 4: Master RS485 Communications Cable
Schematic
Fig. 5: Typical Outdoor Air Temperature Sensor