Figure 8: 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.
6. Connect the 24 VAC supply power wires from the transformer to the converter. No additional
external power adapter is required. Connect the hot and common wires as desired. The NAE
does not require an earth ground connection.
Note:
The 24 VAC power should be connected 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 NAE for M-Bus protocol
1. Connect the Ethernet cable to the RJ-45, 8-pin Ethernet port shown in Figure 1.
2. Connect from the RS232C A or RS232C B serial port on the NAE to the RS-232 connector of the
level converter. Wire to terminals
GND
,
RxD
, and
TxD
as shown in Figure 9.
3. Wire from the
M-
and
M+
terminals on the level converter (Figure 9) to the meters using a free
(star, tree, or line) topology. Specific cabling can vary depending on the topology and site. See
Wiring rules and guidelines for network integrations
.
Note:
If the number of M-Bus unit loads or distances exceeds the specifications of a level
converter, an M-Bus repeater can be wired to the converter to increase the number of unit
loads and distances. The converter shown in Figure 9 is capable of handling up to 6 units
loads, while other models can handle up to 100. See
Bus devices.
4. Connect the 24 VAC supply power wires from the transformer to the removable power terminal
block plug on the NAE (Figure 8).
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. Connect the 24 VAC supply power wires from the transformer to the
-/~
and
+/~
terminals as
11
NAE35/NAE45 Installation Guide
