Moxa Technologies RS-422, RS-485 user manual Solution

Serial Programming Tools

There are 2 solutions to control RS-485 2-wire transmission.

Solution 1

The following model is common in RS-485 2-wire transmission.

sio_SetWr iteTimeouts(por t, 0);	/* Set sio_wr ite() into block mode if for
	Windows NT and Windows 95/98 */
sio_RTS(por t, 1);	/* Tur n on RTS signal. The RS-485
	por t is r eady for tr ansmitting data. */
sio_wr ite(por t, buff, 10);	/* Wr ite 10 byte char acter s in " buff" .
	The	function blocks until last
	char acter tr ansmitted */
sio_RTS(por t, 0);	/* Tur n off RTS signal. The RS-485
	por t is r eady for r eceiving data. */
sio_r ead(por t, buff, 10);	/* Read 10 bytes */
Solution 2		in PComm or API-232 library. It
There is a dedicated RS-485 function

integrates the above functions of solution 1 regarding sending data as one.

sio_putb_x(por t, buff, tick ); /*	1.	Tur n on RTS and r eady for
		tr ansmitting data.
	2.	Send data.
	3.	Wait for tick time.
	4.	Tur n off RTS and r eady for
		r eceiving data. */

For more information on these functions, please refer to PComm library on-line Help file for Windows NT and Windows 95/98 or API-232.txt file for DOS, respectively.

Industio CI-134 Series User’s Manual 4-11