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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

);

National Instruments PCI-8430 User Manual

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