User manual
www.cooperbussmann.com/wirelessresources
Cooper Bussmann 245U-E Wireless Ethernet Modem & Device Server User Manual
17Rev Version 2.19
DB9 Connector Pinouts
Pin Name Direction Function
1 DCD Out Data Carrier Detect
2 RD Out Transmit Data – Serial Data Output (from DCE to DTE)
3 TD In Receive Data – Serial Data Input (from DTE to DCE)
4 DTR In Data Terminal Ready
5 SG — Signal Ground
6 DSR Out Data Set Ready - always high when unit is powered on.
7 RTS In Request to Send
8 CTS Out Clear to Send
9 RI Ring Indicator
RS485 Serial Port
The RS485 port provides for communication between the 245U-E unit and its host device using a multi-drop cable.
Up to 32 devices may be connected in each multi-drop network. Because the RS485 communication medium is
shared, only one of the units on the RS485 cable may send data at any a time. Therefore, communication protocols
based on the RS-485 standard require some type of arbitration.
RS485 is a balanced differential standard, but it is recommended that shielded twisted pair cable be used to
interconnect modules to reduce potential RFI. It is important to maintain the polarity of the two RS485 wires.
AnRS485 network should be wired as indicated in the diagram below and terminated at each end of the network
with a 120-ohm resistor. On-board 120-ohm resistors are provided and may be engaged by operating the single
DIP switch in the end plate next to the RS485 terminals. The DIP switch should be in the “1” (on) position to
connect the resistor. If the module is not at one end of the RS485 cable, the switch should be off.
NOTE Shorter runs of 485 cable may not require the termination resistors to be enabled.
Figure 15 Multidrop Serial