Connecting The N2 Bus; N2 Device Mapping - Johnson Controls TEC2102-3 Installation Instructions Manual

Y2
R3
R3-1
Y2

Connecting the N2 Bus

To connect the N2 Bus:
1. Set the N2 address of the TEC2102-3 Thermostat
per the engineering drawings prior to wiring the
thermostat. (See the Com addr parameter in
Table 2 to set the N2 address for the thermostat.)
Also test for N2 voltage, polarity, and isolation prior
to wiring the thermostat.
2. Observe the polarity when connecting the N2 Bus
wires to the thermostat.
3. After the N2 Bus wires are connected to the first
thermostat, continue in a daisy-chained fashion to
the next thermostat.
Note: The thermostat N2 Bus is self-terminating. The
N2 Bus wiring must be twisted-pair lines. Do not run the
N2 Bus wiring in the same conduit as line voltage
wiring (30 VAC or above) or other wiring that switches
power to highly inductive loads (such as contactors,
coils, motors, or generators).
For more N2 Bus overview information, refer to the N2
Communications Bus Technical Bulletin (LIT-636018)
and the ASC and N2 Bus Networking and
Troubleshooting Guide (LIT-6363003).

N2 Device Mapping

Define the TEC2102-3 Thermostat as a Vendor Device
(VND) when adding the thermostat to the supervisory
controller.
TEC2102-3 N2 Networked Heat Pump Thermostat Installation Instructions
G
Y1 RC C
R2
R1
Separate 24 VAC
Transformer
R2-1 R1-1
Y1
G
Heat Pump Terminal Interface
Figure 6: VDC Switching Application for Heat Pumps
RH W1 O/B
R4
To Auxiliary
Heat Circuit
Note: Use 24 VAC
interface relays R1-1,
R2-1, R3-1, and R4-1
R4-1
(provided by the user).
O/B
RC
The Thermostat Point (Type/Address) is the fixed-point
definition inside the thermostat. The most recent N2
command received by any of the Object Types listed in
Table 1 controls the thermostat.
Overrides take priority over any local adjustment or
command in the thermostat.
If a setpoint is overridden, the thermostat adjusts the
other setpoint, if necessary, to maintain the minimum
deadband between the two setpoints. The setpoints
can be spread farther apart but can never be adjusted
closer than 2F°/1C° apart.
If a supervisory controller commands an override of an
analog or binary object, all local changes attempted
through the thermostat keypad for that object are
ignored until the override is released. For example, if
the supervisory controller sends an override message
to turn System Mode Off, and then the user selects
System Mode On at the thermostat keypad, the
thermostat keeps the System Mode Off.
When an override is released, the object may once
again be changed through the thermostat keypad, but
the thermostat does not retain any data entered at the
thermostat keypad during the override.
All overrides are released automatically after 10
minutes of no communications (for example, if the
network cable is removed from the thermostat, causing
a loss of network communications).
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