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Cooper Bussmann 915U-2 Wireless Mesh I/O and Gateway User Manual
19
Rev Version 1.2.2
RS-232 Port
The 915U-2 module provides an RS-232 serial port that supports operation at data rates up to 230,400 baud. This
port supports Modbus protocol. The RS-232 port is provided by an RJ-45 connector wired as a DCE according to
the EIA-562 Electrical Standard.
RJ-45
Signal
Required
Signal name
Connector
1
RI
Ring Indicator
2
DCD
Data Carrier Detect
3
DTR
Y
Data Terminal Ready
4
GND
Y
Signal Common
5
RXD
Y
Receive Data (from 915U-2)
6
TXD
Y
Transmit Data (to 915U-2)
7
CTS
Clear to Send
8
RTS
Request to Send
RS-485 port with Modbus Support
The 915U-2 module provides an RS-485 serial port that supports operations at data rates up to 230,400 baud.
The default baud rate is 9600 baud, no parity, 8 data bits and 1 stop bit, which matches the 115S serial expansion
module defaults. This port supports the Modbus protocol.
The RS-485 port terminal is hosted on the four-way expansion connector on the bottom edge of the module. An
on-board RS-485 termination resistor provides line attenuation for long runs. As a general rule, termination resistors
should be placed at each end of the RS-485 cable. When using 115S expansion I/O modules, remember to enable
the RS-485 termination resistor switch that is located on the end module.
Figure 10 RS
-
485 Connections