Connecting The N2 Bus; N2 Device Mapping - Johnson Controls TEC2104-3 Installation Instructions Manual

Connecting the N2 Bus

To connect the N2 Bus:
1. Set the N2 address of the TEC2104-3 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 TEC2104-3 Thermostat as a Vendor Device
(VND) when adding the thermostat to the supervisory
controller.
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.
4 TEC2104-3 N2 Networked Multi-Stage Economizer Thermostat Installation Instructions
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).
Metasys® System Person-Machine Interface (PMI)
Do not direct-map any points; instead, run control of
these points through the Control System (CS) object.
The supervisory controller Model Point Type is the
definition inside the model file. Use a CS object to
retrieve the data.
Metasys System Extended Architecture
There must not be a Relinquish Default for the
setpoints if you desire to change them from the
thermostat display. If there is a Relinquish Default for
the setpoints, the supervisory controller always has an
Override for either an Adjusted value or the Relinquish
Default value. Use the Operator Override and the
Release Operator Override to command the setpoint
and release it to local control. At that time, the user is
able to change the setpoint from the local display.