National Instruments PCI-8430, Manual

Page: 107 / 237

DeviceIoControl Windows function on ENET RS-485 hardware,
complete the following steps:
1. Add the following lines to your source code:
#include <winioctl.h>
#define SERIAL_TM_4WIRE
0x80
#define SERIAL_TM_2W_ECHO 0x81
#define SERIAL_TM_2W_DTR 0x81
#define SERIAL_TM_2W_AUTO 0x83
#define IOCTL_SERIAL_SET_TRANSCEIVER_MODE
CTL_CODE(FILE_DEVICE_SERIAL_PORT,37,METHOD_BUFFERED,FILE_ANY_ACCESS)
2. To set the RS-485 transceiver control mode, use
IOCTL_SERIAL_SET_TRANSCEIVER_MODE
and
DeviceIoControl. For example, to set to two-wire Auto
Control mode, use the following code:
ULONG bytecount;
TRANSCEIVER_MODE transceiver_mode = SERIAL_TM_2W_AUTO;
DeviceIoControl(
comhandle,
IOCTL_SERIAL_SET_TRANSCEIVER_MODE,
(PVOID) &transceiver_mode,
sizeof(transceiver_mode),
(PVOID) NULL, 0,
&bytecount,
NULL
);