Johnson Controls NAE55 Installation Manual page 9

3. Wire from the RS-485 terminal on the converter
to the RS-485 port on the vendor device (Figure
12). The RS-485 bus is a two-wire network.
a. Connect the converter's + A terminal to the
device's + (or A) terminal.
b. Connect the converter's - B terminal to the
device's - (or B) terminal.
Figure 12: Connection between converter and
device
4. To add additional vendor devices, wire from one
device to the next in a daisy chain configuration.
The completed wiring should look similar to
Figure 13.
Figure 13: Modbus RTU wiring detail overview
Connecting M-Bus devices
The NAE connects to the M-Bus network devices by
using the M-Bus Level Converter. Two components
are needed: serial connection cable (INT-DX-KAB01)
and the M-Bus Level Converter. (After installation
and wiring are complete, refer to the Network
Engine Commissioning for M-Bus Vendor Integration
Application Note (LIT-12013149) for additional
information.)
1. Connect the RS-232 cable from either RS232C
serial port on the network engine to the RS-232
connection on the M-Bus Level Converter
using cable INT-DX-KAB01 (Figure 14). Wire to
terminals GND, RxD, and TxD (Table 2).
2. Wire from the M- and M+ terminals on the
level converter to the meters using a free (star,
ring, or bus) topology, preferably bus. Specific
cabling can vary depending on the topology and
site. See Wiring considerations 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 14 is capable of handling up to 100 unit
loads. See Ordering information
Bus devices.
3. Connect the 24 VAC supply power wires from
the transformer to the -/~ and +/~ terminals as
shown in Figure 14.
for a list of M-
NAE55/NIE55 Installation Guide 9