RTCU LX4 pro Technical Manual V1.00
Advanced Industrial M2M/IoT Gateway
Logic IO ApS.
Ph: (+45) 7625 0210
Holmboes Allé 14
Fax: (+45) 7625 0211
8700 Horsens
Page 18 of 39
Email: [email protected]
Denmark
RS232 port
This port can be used as a general-purpose RS232 serial port with hardware handshake signals.
RJ45 connector overview.
Pin
Name
Description
11
SGND
Signal ground
14
TXD
Transmit data for the RS232 port
15
RXD
Receive data for the RS232 port
16
RTS
Request to send for the RS232 port
17
CTS
Clear to send for the RS232 port
RS485 Port
RS485 is a multi-drop network with a maximum of 32 nodes connected simultaneously to the bus.
Each RS485 bus contains an RSA and an RSB signal and a signal ground, which must always be
connected to the common signal ground for all nodes connected to the RS485 bus!
The maximum cable length for the RS485 bus is according to the EIA/TIA-485-A standard (max.
1000m @ <100kbit); this limit is highly influenced by the quality of the cable, signaling rate, noise etc.
At longer cable lengths, noisy environments, or high communication speeds, it might be necessary to
terminate the transmission line with a 120
1
ohm resistor at each end of the transmission line to
terminate it and avoid signal reflections. If the RTCU LX4 pro is used as an endpoint node, the jumper
for the RS485 port can be inserted in order to terminate the RS485 communication lines with 120
Ω
. By
default, the RS485 communication lines are not terminated with 120
Ω
. For placement and
configuration of the hardware jumpers inside the unit, please refer to the configuration guide in
Appendix A.
Please note:
For best performance, protection, and noise immunity, it is advised to use a shielded
cable to connect the device to the RS485 communications bus.
1 Assuming use of a CAT5 twisted pair cable
