usbHostEnable (Function)

The usbHostEnable function enable/disable support for USB devices. When disabled the USB power is removed from the USB host port.

Please consult the technical manual for details on how many USB host ports a specific device offers.

The USB host is disabled as default, and must be enabled before devices can be discovered using usbHostEnumerate.

Input:

port : SINT  (1 .. 127)

The USB host port to enable/disable. (1=usb1, 2=usb2, etc.)

enable : BOOL (false/true)

Returns: INT

Declaration:

FUNCTION usbHostEnable : INT;
VAR_INPUT
  port : SINT;
  enable : BOOL;
END_VAR;

Example:

INCLUDE rtcu.inc
 
VAR_INPUT
  doEnable : BOOL; | enable/disable USB host
END_VAR;
 
VAR_OUTPUT
  isEnabled : BOOL := TRUE; | is USB host enabled
END_VAR;
 
PROGRAM test;
BEGIN
  IF doEnable XOR isEnabled THEN
    // Enable/Disable USB host
    usbHostEnable(port:=1,enable:=doEnable);
    isEnabled := doEnable;
  END_IF;
END;
END_PROGRAM;