User`s manual

CP-132 Series Serial Programming Tools
4-6
How to transmit and receive data for Windows NT, 95/98 & DOS
We recommend you to configure Industio CI-132 Series ports as follows in order to acquire precise timing
control in RS-485 2-wire transmission.
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_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
last character 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
There is a dedicated RS-485 function in PComm or API-232 library. It integrates the above functions of solution
1 regarding sending data as one.
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, please refer to PComm library on-line Help file for Windows NT and
Windows 95/98 or API-232.txt file for DOS, respectively.