Use XML tags and structure to customize an FPGA configuration file.

The first line of the FPGA configuration file includes the XML version. All other tags inside the file must be enclosed in <FPGADMAChannelData> tags.
<?xml version="1.0"?>
<FPGADMAChannelData>
<!-- Insert tags here -->
</FPGADMAChannelData>

XML schema files (.xsd) are definition files that constrain an XML file to a certain format. You can add a schema file to most XML editing tools when writing an XML file. Use the NI VeriStand FPGA DMA.xsd schema file in the <Common Data>\FPGA directory to minimize syntax and formatting errors when you create an FPGA configuration file.

The following table displays the XML tags you can use in the FPGA configuration file. To see how to implement these tags, refer to the example FPGA Configuration File Structure.
Tag Required? Parent tag Number of child tags Description
FPGADMAChannelData Yes — — Contains all channel definitions.
Version Yes FPGADMAChannelData 1 Defines which version of the channel tags you used to create the FPGA configuration file. For example, if you used the tags defined in this table, you must set the Version tag to 2.0.
Bitfile No FPGADMAChannelData 1 Specifies the name of the corresponding bitfile (.lvbitx). The bitfile must be saved in the same directory as the FPGA configuration file. The default value is <name of FPGA configuration file>.lvbitx.
Categories No FPGADMAChannelData 1 Contains multiple category definitions and describes the hierarchy of the channels visible in System Explorer. You cannot nest <Categories>.
Category Yes Categories 0 or more Defines a single level of the configuration tree hierarchy in System Explorer. You can nest <Category>. If you do not specify <Category> elements, the configuration tree hierarchy is inferred based on the <Category> tags contained within individual channels.
Name Yes Category 1 Defines the name of <Category> in System Explorer configuration tree. <Name> must be unique within its set of siblings.
Description No Category 1 Specifies the description of <Category> in System Explorer.
Symbol No Category 1

Defines the symbol for <Category> in the System Explorer window configuration tree.

You can select from the following values:
  • Default
  • AI
  • AO
  • DI
  • DO
  • PWM In
  • PWM Out
DMA_Read Yes FPGADMAChannelData 1 Contains packet definitions. Specifies the content of the DMA_Read FIFO.
DMA_Write Yes FPGADMAChannelData 1 Contains packet definitions. Specifies the content of the DMA_Write FIFO.
Packets Yes DMA_XXX* 1 Defines the number of unsigned 64-bit packets contained in the DMA FIFO. If the number of <Packet> elements is less than the number specified in <Packets>, VeriStand ignores the last <Packet>.
Packet No DMA_XXX 1 or more

Specifies the content of a single unsigned 64-bit channel in the DMA FIFO. You do not have to use all of the available bits in a packet. You also can specify an empty packet using the <Packet/> tag with no closing tag. An empty <Packet> element specifies a packet that is to be ignored.

You might want to use an empty packet for the first DMA_Read packet because the first bit of the first DMA_Read packet contains a Late Status field by default. If you specify an empty packet for the first DMA_Read packet, this unusable Late Status bit does not appear in System Explorer. If you want the Late Status bit to be visible in System Explorer, specify it as a Boolean channel in the first DMA_Read packet.
I8 No Packet 0 or more Specifies a signed 8-bit channel in the DMA FIFO.
U8 No Packet 0 or more Specifies an unsigned 8-bit channel in the DMA FIFO.
I16 No Packet 0 or more Specifies a signed 16-bit channel in the DMA FIFO.
U16 No Packet 0 or more Specifies an unsigned 16-bit channel in the DMA FIFO.
I32 No Packet 0 or more Specifies a signed 32-bit channel in the DMA FIFO.
U32 No Packet 0 or more Specifies an unsigned 32-bit channel in the DMA FIFO.
I64 No Packet 0 or more Specifies a signed 64-bit channel in the DMA FIFO.
U64 No Packet 0 or more Specifies an unsigned 64-bit channel in the DMA FIFO.
Boolean No Packet 0 or more Specifies a Boolean channel in the DMA FIFO.
FXPI32 No Packet 0 or more Specifies a fixed-point signed 32-bit channel in the DMA FIFO. Use this data type if the word length you specify in <FXPWL> is less than or equal to 32 bits. The channel occupies the full 32 bits in the packet, but only use the bits corresponding to the word length.
FXPU32 No Packet 0 or more Specifies a fixed-point unsigned 32-bit channel in the DMA FIFO. Use this data type if the word length you specify in <FXPWL> is less than or equal to 32 bits. The channel still occupies the full 32 bits in the packet, but only the bits corresponding to the word length are used.
FXPI64 No Packet 0 or more Specifies a fixed-point signed 64-bit channel in the DMA FIFO. Use this data type if the word length you specify in <FXPWL> is greater than 32 bits. The channel still occupies the full 64 bits in the packet, but only the bits corresponding to the word length are used.
FXPU64 No Packet 0 or more Specifies a fixed-point unsigned 64-bit channel in the DMA FIFO. Use this data type if the word length you specify in <FXPWL> is greater than 32 bits. The channel still occupies the full 64 bits in the packet, but only the bits corresponding to the word length are used.
PWM No Packet 0 or more Specifies a pulse width modulation (PWM) channel in the DMA FIFO. Consists of two 32-bit numbers, totaling 64 bits. The lower 32 bits represent the low time of the PWM channel. The higher 32 bits represent the high time of the PWM channel.
Void No Packet 0 or more Specifies unused bits in the middle of a packet.
Size Yes Void 1 Specifies the number of bits to ignore in a packet.
Name Yes any data type 1 Defines the name of the channel in System Explorer. This tag must be unique within its category.
Description No any data type 1 Specifies the description of the channel in System Explorer.
Category No any data type 1 Specifies the full path of the category where the channel should appear. If you do not specify <Category>, the default is Input for channels in the DMA_Read FIFO and Output for channels in the DMA_Write FIFO.
InitialValue No any data type 1

Specifies the value of the channel until its value is set. The default value is 0.

Use <InitialValue> for output channels.
Scale No any data type 1

Specifies the range of the scale in engineering units. For PWM and fixed-point data types, the default value is 1. For all other data types, the default value is the full positive range of the data type.

For example, the full positive range of the signed 8-bit data type is 127, and the full positive range of the unsigned 8-bit data type is 255.
Offset No any data type 1 Specifies the offset of the scale in engineering units. The default value is 1.
Unit No any data type 1 Specifies the units of the channel. If you do not specify the units, the channel has no units.
Symbol No any data type 1
Defines the symbol of the channel in System Explorer. You can select from the following values:
  • Default
  • AI
  • AO
  • DI
  • DO
  • PWM In
  • PWM Out
FXPWL No any fixed-point data type 1 Specifies the fixed-point word length.
FXPIWL No any fixed-point data type 1 Specifies the fixed-point integer word length. The default value is 0.
PWMPeriod No PWM 1 Specifies the pulse width modulation (PWM) period for output channels. The default value is 100000.
Parameters No any data type 1 Specifies the parameters associated with the parent channel.
any data type except for Void Yes Parameters 1 or more

Defines a parameter associated with the parent channel and specifies the data type of that parameter. <Parameters> accepts the same data types as <Packet>. However, Void is not a valid data type for <Parameters>.

If you use the Boolean data type, or the signed or unsigned 8-bit, 16-bit, 32-bit, or 64-bit data types, the associated FPGA VI control must be of the same data type. If you use the fixed-point or PWM data types, the data type of the associated FPGA VI control must correspond as follows:
  • FXPI32 — I32
  • FXPI64 — I64
  • FXPU32 — U32
  • FXPU64 — U64
  • PWM — U64
Name Yes any data type except for Void 1 Defines the name of the parameter on the channel configuration page in System Explorer.
ControlName No any data type except for Void 1 Specifies the name of the associated control in the corresponding FPGA VI. The default is the same as <Name>. The control referenced in the parameter must exist in the FPGA VI.
InitialValue No any data type except for Void 1

Specifies the parameter value when System Explorer loads the FPGA configuration file. The default value is 0.

You can change parameter values in System Explorer. You cannot change parameter values at run time.
Scale No any data type except for Void 1

Specifies the range of the scale in engineering units. For PWM and fixed-point data types, the default value is 1. For all other data types, the default value is the full positive range of the data type.

For example, the full positive range of the signed 8-bit data type is 127, and the full positive range of the unsigned 8-bit data type is 255.
Offset No any data type except for Void 1 Specifies the offset of the scale in engineering units. The default value is 1.
* DMA_XXX denotes both DMA_Read and DMA_Write.