Moxa Technologies 4-6 CP-132U Series User’s Manual, Solution, NT and Windows 95/98, sioRTSport

and receiving), since it is automatically managed with the board’s built-in intelligent hardware mechanism. This means that RS-485 programming using ADDC™ mode is just as simple and straightforward as RS-232 or RS-422 programming.

How to transmit and receive data for Windows 95/98NT/2000/XP/2003

In order to acquire precise timing control for RS-485 2-wire transmission, we recommend that you configure your CP-132UL Series ports as described below.

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

Solution 1

The following method is commonly used for RS-485 2-wire transmission:

sio_SetWriteTimeouts(port, 0); /* Set sio_write() into block mode if for Windows

	NT and Windows 95/98 */
sio_RTS(port, 1);	/* Turn on RTS signal. The RS-485 port is ready for
	transmitting data. */
sio_write(port, buff, 10);	/* Write 10 byte characters in "buff". The function
	blocks until the last character is transmitted */
sio_RTS(port, 0);	/* Turn off RTS signal. The RS-485 port is ready for
	receiving data. */
sio_read(port, buff, 10);	/* Read 10 bytes */

Solution 2

The PComm or API-232 library includes a dedicated RS-485 function that integrates the functions described in solution 1 above into one function:

sio_putb_x(port, buff, tick );	/* 1.	Turn on RTS and ready for transmitting data.
	2.	Send data.
	3.	Wait for tick time.
	4. Turn off RTS and ready for receiving data. */

For more information on these functions, refer to the PComm library’s on-line Help file for Windows 95/98/NT/2000/XP/2003.

4-6 CP-132U Series User’s Manual