LabVIEW 2018 FPGA Module Help
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Requires: FPGA Module
Right-click a FIFO control or constant and select Configure FIFO Type from the shortcut menu to display this dialog box.
Use this dialog box to configure the FIFO control or constant. You can specify the data type of the FIFO and the supported methods. When you use a FIFO control as an input on a subVI, the input accepts only FIFO items that support the data type and methods you enabled for the FIFO control.
This dialog box includes the following components:
- FIFO Data Type—Specifies the data type of the data in the FIFO. You can select a fixed-point (FXP) data type; a Boolean data type; an 8-, 16-, 32-, or 64-bit signed or unsigned integer data type; or a single-precision floating-point (SGL) data type. You also can select a custom control as the data type. If you select FXP, configure the data type in the Fixed-Point Configuration section.
|Note DMA and peer-to-peer FIFOs do not support custom data types.|
- Fixed-Point Configuration—Sets the configuration settings for fixed-point data. Set Data Type to FXP to enable the fixed-point settings. LabVIEW automatically configures the Range based on the Encoding settings you specify.
|Note Fixed-point data type FIFOs do not include an overflow bit when transferring data. To transfer the overflow bit, use a separate FIFO. You also can specify a wider data type for the FIFO so that you can manipulate the data to add the overflow bit when writing to the FIFO and subtract the overflow bit when reading from the FIFO.|
- Encoding—Sets the binary encoding settings for a fixed-point value.
- Signed—Sets the fixed-point data to represent a signed number.
- Unsigned—Sets the fixed-point data to represent an unsigned number.
- Word length—Sets the number of bits that LabVIEW uses to represent the possible fixed-point values.
- Integer word length—Sets the number of integer bits, or the number of bits to shift the binary point to reach the most significant bit, for all the possible fixed-point values. Integer word length can be positive or negative.
- Range—Indicates the range for a fixed-point value.
|Note The fields you use to specify these values display the values in double-precision floating-point representation, so the precision of Maximum, Minimum, and Delta might not be exact in terms of fixed-point representation. However, the deviation is very small.|
- Minimum—Indicates the minimum value for the fixed-point data range.
- Maximum—Indicates the maximum value for the fixed-point data range.
- Delta—Indicates the maximum distance between any two sequential numbers in the fixed-point data range.
- Custom Control—Opens a dialog box in which you can navigate to the custom control you want to use. This button appears only when you select Custom Control in the Data Type pull-down menu.
- Supported Methods—Use this section to set the methods you can use with the FIFO Method Node.
- Write—Enables support for the Write and Get Number of Elements to Write methods.
- Number of Elements per Write—Specifies the number of elements that the FPGA VI can write to the DMA FIFO each clock cycle. The default is 1.
- Read—Enables support for the Read and Get Number of Elements to Read methods.
- Number of Elements per Read—Specifies the number of elements that the FPGA VI can read from the DMA FIFO each clock cycle. The default is 1.
- Clear—Enables support for the Clear method for a target-scoped or VI-defined FIFO.
- Peer-to-Peer Streaming Methods—Enables support for peer-to-peer FIFOs. Methods for peer-to-peer FIFOs are not compatible with the Clear method. Individual peer-to-peer FIFOs do not support both the Read and Write methods.
The following methods are supported when you place a checkmark in the Peer-to-Peer Streaming Methods checkbox.
The following additional methods of the FIFO Method Node are supported when you place a checkmark in the Peer-to-Peer Streaming Methods and Write checkboxes.
The following additional methods of the FIFO Method Node are supported when you place a checkmark in the Peer-to-Peer Streaming Methods and Read checkboxes.
- Flush—Enables support for the Flush method for a DMA target-to-host FIFO or a peer-to-peer writer FIFO.