Rockwell Automation 1747-PCIS API Software - Open Controller - Manual (Page 35)

Publication 1747-UM002A-US-P - June 2000
Developing Applications 3-3
The API has a defined constant specifying the total number of bytes
available for the three segmenters This constant is specified as:
OCSEGMENTSIZELIMIT
Once the scanner has been initialized properly it cannot be
re-initialized unless it is reset with the OC_ResetScanner function.
Once the scanner is reset, scanner communications are disabled again
until the scanner is initialized. The host application can call
OC_GetScannerStatus to determine if the scanner has been initialized.
If the scanner was previously initialized, the host application can
retrieve the initialization partition information with the
OC_GetScannerInitInfo function instead of resetting and re-initializing
the scanner.
Configure the scanner
To access I/O modules in a rack, you must define the rack sizes and
installed module types for the scanner. You can either create a specific
configuration or read the current configuration. The scanner cannot
be set to Scan mode until it has been configured (received a valid
scanner configuration).
If the scanner is in Scan mode and the host application has not
downloaded a scanner configuration, the scanner has already been
configured. To control I/O, use OC_GetIOConfiguration to retrieve
the current scanner configuration.
The application can read the current I/O configuration with the
OC_GetIOConfiguration function. If the scanner is not in Scan mode,
this function returns the current scanner configuration which can be
downloaded to the scanner using OC_DownloadIOConfiguration.
If the application requires a specific I/O configuration, the application
can define the I/O configuration structure with the rack sizes and
module types installed in each slot. The application passes this
configuration structure to OC_CreateIOConfiguration.
OC_CreateIOConfiguration returns a scanner configuration that can be
downloaded to the scanner. For more information, see chapter 5.
Once a valid scanner configuration is successfully downloaded to the
scanner via OC_DownloadIOConfiguration, the application can set the
scanner to Scan mode and control I/O.
Both OC_CreateIOConfiguration and OC_GetIOConfiguration build
the configuration data from an internal database of supported I/O
modules.