Casio IT-2000W Technical Reference Manual page 217

Release of COM Port
Releases the COM port and turns off the power to the COM port.
SYNTAX
#include "obrlib.h"
void FAR PASCAL _export OBR_Close();
INPUT
None
OUTPUT
None
Note :
Call this function if completing the use of the OBR (i.e. terminating the application program).
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