Wiring to terminal block by cutting DB9 cable

How do you wire RS232 or RS485 radio modems to a terminal block when the signals are available only on the DB9 connector?

The easiest method is to cut the DB9 straight through serial cable supplied with the PKG-R radio modem and strip the wires inside to connect them to the terminal block directly.


The individual wires inside the DB9 cable are small diameter stranded wires and may break off. It is not recommend that this cable be used in a vibration or movement prone environment because of the risk of breaking the wires. Use the DB9 to RJ45 adaptors instead (search knowledge base).

For convenience here is a table showing  the wires inside the DB9 cable and which signals they are connected to in different modes of operation.

DB9 Pin   RS232 (DCE) RS485 4-wire RS485 2-wire
1   DCD    
2   RXD TX- T/R- (A)
3   TXD RX-  
4   DTR    
5   GND GND  
6   DSR    
7   RTS RX+  
8   CTS TX+ T/R + (B)
9   PWR*(RI) PWR* PWR*

*Optionallly provide power to radio through Pin 9 of DB9 (DB0 pin 9 is connected to center (positive) lead of power jack)

Last updated: Aug 23, 2017

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