Figure 10: 24 VAC Supply Power Wiring
Note:
Power supply wire colors may be different on transformers not manufactured by Johnson Controls. Follow
the transformer manufacturer’s instructions and the project installation drawings.
9. Terminate the 24 VAC supply power wires from the transformer to the converter. No additional external power
adapter is required. Terminate the hot and common wires as desired. The NIE does not require an earth ground
connection.
Note:
The 24 VAC power should be terminated to all network devices so transformer phasing is uniform across
the devices. Powering network devices with uniform 24 VAC supply power phasing reduces noise,
interference, and ground loop problems.
Wiring the NIE for M-Bus Protocol
1. Connect the Ethernet cable to the RJ-45, 8-pin Ethernet port shown in
.
2. Connect from the RS232C serial port on the NIE to the RS-232 connecter of the level converter. Wire to terminals
GND
,
RxD
, and
TxD
as shown in
.
3. Terminate the
M-
and
M+
wires on the level converter (
) to the meters using a free (star, tree, or line)
topology. Specific cabling can vary depending on the topology and site. See
Wiring Rules for Networks and Field
Note:
If the number of M-Bus unit loads or distances exceeds the specifications of a level converter, you can
connect an M-Bus repeater to the converter to increase the number of unit loads and distances. The
converter shown in
is capable of handling up to 6 units loads, while other models can handle
up to 100. See
NIE29 Model Ordering Information Table
for a list of M-Bus devices.
4. Terminate the 24 VAC supply power wires from the transformer to the removable power terminal block plug on
the NIE (
).
Note:
Power supply wire colors may be different on transformers not manufactured by Johnson Controls. Follow
the transformer manufacturer’s instructions and the project installation drawings.
5. Terminate the 24 VAC supply power wires from the transformer to the
-/~
and
+/~
terminals as shown in
10
NIE29 Installation Instructions
