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Remote Setpoints
= 40
16
= 2.5°F
Setpoint (°F)
= 40 + 2.5
= 42.5
PWM
The Pulse Width Modulation input is in the form of a 1 to
11 second relay contact closure that ap plies 115VAC to
the I/O Board TB4-19 for 1 to 11 sec onds. As shown in
Fig. 14, connect dry closure relay contacts be tween I/O
Board TB4-19 (input) and TB4-1 (115VAC). A con tact
closure time (pulse width) of 1 second pro duc es a 0°F
offset. An 11 second closure produces the max i mum al-
lowed offset (10 or 20°F above the Local Setpoint value).
The relay contacts should close for 1 to 11 sec onds at
least once every 30 minutes to main tain the setpoint to
the desired value. If a 1 to 11 second
closure is not received within 30 minutes of the last
clo sure, the setpoint is defaulted to the Local setpoint
val ue. A closure is only accepted at rates not to exceed
once every 70 seconds. This input will only be ac cept ed
in DIGITAL Remote mode. Calculate the setpoint for
various pulse widths as follows:
Offset (°F) =
(pulse width in seconds – 1)(Remote Re set Temp Range)
10
124
Setpoint (F°) = Local Setpoint + Offset
For example, if the relay contacts close for 5 seconds and
the Remote Reset Temp Range setpoint is pro grammed
to 10°F and the Local Leaving Chilled Liq uid Tempera-
ture setpoint is programmed for 40°F, the setpoint would
be set to 44°F as follows:
Offset (°F)
= (5 – 1)(10)
= (4)(10)
= 40
10
= 4°F
Setpoint (°F)
= 40 + 4
= 44°F
RS-232
As shown in Fig. 11, a Setpoint can be re ceived in se ri al
data form at the Microboard COM 4B serial port (J2)
from the MicroGateway.
FORM 160.54-M1(503)
10
10
YORK INTERNATIONAL
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