User Manual

1.5.2 Using a 3-wire RS-232 port
There are 3 wires as following:
GND
7521/7521D
7522/7522D
7523/7523D
7522A/7522AD
7524/7524D
7527/7524D
TXD
RXD
RXD
TXD
RI
CTS
RTS
DSR
GND
DTR
RS-232 Device
DCD
• Connect RXD to TXD of RS-232 device
• Connect TXD to RXD of RS-232 device
• Connect GND to GND of RS-232 device
7521/2/2A/3/4/7 Series Hardware User’s Manual, Ver. 1.5 Sep/2002, 7Mh-001-15 -----33