7188XA/B/C & 7521/2/2A/3/4/7 Series Hardware User’ s Manual, Ver. 3.0 Sep/2002, 7Mh-001-20 -----
69
2.6 The RS-485 Port & Self-Tuner ASIC
The 2-wire RS-485 port is designed to directly drive 7000 series modules.
It is a half-duplex 2-wire RS-485 network. Send/receive directional control in
a 2-wire RS-485 network is very important. Therefore, the 7188X/7521 series
equip a Self-Tuner ASIC controller for all RS-485 ports. The Self-Tuner ASIC
controller will auto detect & control the send/receive direction of the RS-485
network. In this main, the application program does not have to worm about
the send/receive direction control of the RS-485 network. For example, the
software program for one-to-one communication is nearly the same.
RS-232
à
TXD, RXD, GND
RS-485
à
Data+, Data-
7188X/7521
7188X/7521
7188X/7521
7188X/7521
ToCom(port, sent_data);
/* send one sent_char to RS-232/RS-485 */
/*
no direction control
*/
while IsCom(port);
/* wait one echo_char from RS-232/RS-485 */
echo_data=ReadCom(port); /* read this echo_data
*/
2-wire RS-485 network
Send/receive direction
Auto detect/control
Self-Tuner ASIC
Inside
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