Protech Systems BU-2509 User Manual page 21

COM3/COM4/COM5/COM6 CONNECTOR
COM3, COM4, COM5, COM6: COM Connector, fixed as RS-232.
PIN ASSIGNMENT
1 DCD#
2 RX
3 TX
4 DTR#
5 GND
Note: Pin 9 is selectable for RI, +5V or +12V for
COM3 and COM4 only.

BU-2509 USER S MANUAL
Chapter 2 Hardware Configuration
PIN ASSIGNMENT
6 DSR#
7 RTS#
8 CTS#
9 RI#
10
COM3/
COM4/
COM5/
COM6
Page: 2-9