Johnson Controls NIE39 Installation Instructions Manual page 7

Note: The maximum cable length between devices connected though an RS-232 line depends on the baud
rate used. In general, it should not exceed 15 meters at 9600 baud.
5. Wire from the RS-485 terminal on the converter to the RS-485 port on the vendor device
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.
c. If the device has a Signal Ground or Reference terminal, connect this to the converter's CG2 terminal.
6. To add additional vendor devices, wire from one device to the next as shown in
may be connected to each terminal to ensure the daisy chain configuration. See
for Network Integrations
The completed wiring should look similar to
NIE39/NIE49 Installation Instructions
Figure 6: Connection Between Converter and Device
for the Modbus protocol.
Figure 7: Daisy Chained Devices
Figure 8.
(Figure 6). The RS-485
Figure 7. No more than two wires
Wiring Rules and Guidelines
7