Communication bus and supply
power table
Table 6: Communication bus and supply power terminal blocks, functions, ratings, requirements, and
cables
Terminal block/Port label Terminal labels
Function, electrical ratings/
Requirements
Recommended cable type
1
+
-
N2/FC Bus Communications
COM
Signal Reference (Common) for bus
communications
N2/FC BUS
2
SHLD
Isolated terminal (optional shield drain
connection)
Use existing cable or 18 AWG
+
-
SA Bus Communications
COM
SA Bus Signal Reference and 15 VDC
Common
SA BUS
SA PWR
15 VDC Supply Power for Devices on
the SA Bus
0.6 mm (22 AWG) stranded, 4-wire
(2 twisted-pairs), shielded cable
recommended
Note:
The + and - wires are one
twisted pair, and the COM and
SA PWR are the second twisted
pair.
TSTAT
TSTAT
RJ-45 8-Position Modular Connector
pr15 VDC Power for:
•
BTCVT
•
MAP Gateway
•
VAV Balancing Tool
•
One-to-One Wireless Receiver
24 AWG 3-pair CAT 3 Cable <30.5 m
(100 ft)
HOT
24 VAC Power Supply - Hot
Supplies 20–30 VAC (Nominal 24 VAC)
24~
COM
24 VAC Power Supply Common
The
-0 models isolate this terminal from all
other commons.
The -1 models only isolate this terminal
from the FC bus common.
0.8 mm to 1.0 mm²
(20 to 18 AWG) 2-wire
1
To determine wire size and cable lengths for cables other than the recommended cables, see Table 5.
2
The N2/FC Bus wiring recommendations in this table are for N2 bus communications at 9,600 baud. For more information, refer to
the
N2 Communications Bus Technical Bulletin (LIT-636018)
.
3
The MAP Gateway serves as a replacement for the BTCVT, which is no longer available for purchase, but continues to be supported
on select controllers.
Setup and adjustments
Important:
Electrostatic discharge can
damage controller components. Use proper
electrostatic discharge precautions during
installation, setup, and servicing to avoid
damaging the controller.
Setting the device address
Metasys
field controllers are subordinate devices on
N2 buses. Before operating field controllers on a
bus, you must set a valid and unique device address
for each controller on the bus.
You set a field controller’s device address by setting
the positions of the switches on the Device Address
VMA1826/1832 VAV Controller Installation Guide
19
