Advantech HMI-640S - Manual (Page 91)

Appendix A Cabling for RS-232 Port 81
25-pin NULL Modem Cable:
Remoet host
serial port
connector
Calling system
serial port
connector
Signal
2 3 Transmit Data
3 2 Receive Data
4 5 Request to Send
5 4 Clear to Send
6, 8 20
Data Set Ready
and Carrier Detec
7 7 Signal Ground
20 6, 8
Data Terminal
Ready