Rockwell Automation Allen-Bradley ControlLogix 1756-MVI Programming Reference Manual page 96

5-8 Serial Port API
Publication 1756-RM004B-EN-P - October 2000
MVIsp_Close
Syntax:
int MVIsp_Close(int comport);
Parameters:
comport port to close
Description:
This function is used by an application to release control of the a
communications port. comport must be previously opened with
MVIsp_Open.
comport specifies which port is to be closed. The valid values for the
1756-MVI module are COM1 (corresponds to PRT1), COM2
(corresponds to PRT2), and COM3 (corresponds to PRT3).
The handshake lines DTR and RTS of the port specified by comport
are turned off by MVIsp_Close.
Once the API has been opened, this function should
IMPORTANT
always be called before exiting the application.
Return Value:
MVI_SUCCESS
MVI_ERR_NOACCESS
Example:
MVIsp_Close(COM1);
See Also:
MVIsp_Open
port was closed successfully
comport has not been opened