Figure 4: SA bus terminal block wiring
Modular ports
The modular and FC Bus ports on the face of the
VMA are RJ-12 (6-position) modular jacks as shown
in Figure 5.
Figure 5: Pin Number Assignments for
Sensor (SA Bus and FC Bus) Ports on
VMA1615/1626/1628/1630 Controllers
The modular SA Bus port provides a connection for
the Wireless Commissioning Converter (BTCVT),
VAV Balancing Tool, DIS1710 Local Controller
Display, WRZ78xx Series One-to-One Wireless
Transmitter, and NS Series sensors. The modular
FC Bus port provides a connection for the Wireless
Commissioning Converter and the ZFR/ZFR Pro
Wireless Router.
Note:
Do not use the modular SA Bus port and
the terminal block SA Bus simultaneously. Only
use one of these connections at a time.
Supply power terminal block
The 24 VAC supply power terminal block is a
gray, removable, 2-terminal plug that fits into a
board-mounted jack on the upper left of the VMA
controller.
Wire the 24 VAC supply power wires from the
transformer to the HOT and COM terminals on the
terminal plug as shown in the following figure. See
Table for more information.
Figure 6: 24 VAC supply power terminal block
wiring
Important:
Exercise caution while rewiring
the power plug when replacing a VMA1610
or VMA1620 controller with a VMA1615 or
VMA1630 controller. The supply power terminal
on a new VMA is a two-position terminal block
(Figure 6). A VMA1610 or VMA1620 controller
uses a three-position terminal block, and the
center position is not used. Stray wire strands
may make contact and cause a short circuit
across the 24 VAC power supply.
The supply power wire colors may be different on
transformers from other manufacturers. Refer to
the transformer manufacturer’s instructions and
the project installation drawings for wiring details.
Important:
Connect 24 VAC supply power to
the controller and all other network devices
so that transformer phasing is uniform across
the network devices. Powering network
devices with uniform 24 VAC supply power
phasing reduces noise, interference, and
ground loop problems. The controller does not
require an earth ground connection. However,
when grounding the secondary of the 24 VAC
transformer is required, only one connection to
ground should be made near the transformer.
See the following figure.
VMA1615/1626/1628/1630 VAV Controllers Installation Guide
7
