Rockwell Automation 1747-PCINT API Software for 1746 I/O - Manual (Page 79)

OC_GetInputImage UpdateCounter Library of Routines 6–25
Publication 1747-6.5.3 June 1998
OC_GetInputImage
UpdateCounter OC_GetInputImageUpdateCounter reads the value of the input image update
counter from the scanner and places it into
count .
Syntax:
int OC_GetInputImageUpdateCounter(HANDLE handle, BYTE *count);
Parameters:
Description:
The input image update counter is incremented by the scanner after each input scan.
The input image update counter is only incremented if the scanner is in Scan mode, input scans are enabled,
and inputs are present. Use the counter to determine whether a change occurred; the value of the counter is
not important. It is possible to configure a system with no inputs; in this case, the input image update counter
would not be incremented.
Return Value:
Considerations:
Supported in the DOS API library and the Windows NT API library
Example:
HANDLE Handle;
BYTE count;
int retcode;
retcode = OC_GetInputImageUpdateCounter( Handle, &count );
Parameter: Description:
handle Must be a valid handle returned from OC_OpenScanner
count Contains the value of the input image update counter
Name: Value: Description:
SUCCESS
0
input image update counter was read successfully
ERR_OCACCESS 2
handle does not have access to scanner
ERR_OCINIT 5 scanner has not been initialized, see OC_InitScanner