Owning Palette: FPGA I/O Functions
Requires: FPGA Module
To add additional FPGA I/O items to an FPGA I/O Node, right-click the I/O Item section and select Add Element from the shortcut menu. You also can expand or contract the FPGA I/O Node by clicking the upper or lower edge of the node with the Positioning tool and dragging the edge up or down.
|FPGA I/O In is an optional input that allows you to specify the FPGA I/O item to read or write using an FPGA I/O control or constant. To use an FPGA I/O control as a connector pane input, the FPGA VI must be configured for reentrant execution.|
|FPGA I/O Out returns the FPGA I/O item on which you configure the node to operate.|
|I/O Item is the data read from or written to the FPGA I/O item you specify. For FPGA I/O items that support the read operation, this parameter is an indicator by default. For I/O items that do not support the read operation, this parameter is a control by default. For FPGA I/O items that support reading and writing, this parameter can be either a control or an indicator. This parameter changes to a control or indicator when you right-click an element in the node and select Change to Write or Change to Read, respectively.|
When you select an element on the node without wiring a value to FPGA I/O In, the name of this parameter changes to match the name of the FPGA I/O item you specify.
When you right-click the element section of the FPGA I/O Node and select Select FPGA I/O from the shortcut menu, LabVIEW displays the FPGA I/O items that appear in the Project Explorer window below the same FPGA target as the FPGA VI you are currently editing. You also can right-click the element selection and select Add New FPGA I/O to add new FPGA I/O items under the FPGA target.
Digital input and output (DIO) resources can perform both read and write operations. To change the operation of an FPGA I/O item, right-click the element and select Change to Read or Change to Write from the shortcut menu. Use the FPGA I/O Method Node configured with the Set Output Enable method to change the direction of a Digital Input and Output I/O resource.
When you configure an I/O Node with multiple I/O items, LabVIEW displays FPGA I/O In, FPGA I/O Out, and I/O Item parameters for each I/O item. When you configure an I/O Node with multiple I/O items, the execution timing of the I/O items depends on the specific hardware devices and I/O items you use. Some FPGA I/O operations execute in parallel, while others execute sequentially.
|Tip Right-click an element in the FPGA I/O Node and select Find Item in Project from the shortcut menu to highlight the I/O item in the Project Explorer window.|
Error Handling Details
You can right-click the FPGA I/O Node on the block diagram and select Show Error Terminals from the shortcut menu to add standard LabVIEW error in and error out parameters to the function. If an error occurs, you might receive incorrect data. Add error terminals to be sure the data you receive is valid. FPGA targets might report errors differently. Refer to the specific FPGA target hardware documentation for information about how specific FPGA targets report errors.
|Note Adding error in and error out parameters increases the amount of space the function uses on the FPGA target. The error in and error out parameters also can cause slower execution on the FPGA target.|