Acquiring Data from a Module (FPGA Interface)

NI CompactRIO Device Drivers Help

Edition Date: December 2017

Part Number: 373197L-01

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The information in this topic applies to the following modules:

The module has input channels that are sampled simultaneously at the data rate for which you have configured the module. Use the Start and Stop channels to put the module in and out of acquisition mode, in which the module can only acquire data. Use the FPGA I/O Node to read the data from the module. While the module is in acquisition mode, you cannot perform other operations with the module, such as accessing properties or, for some modules, TEDS information.

Note  You must create FPGA I/O items for the module before you can configure the items using the FPGA I/O Node.

Putting the Module in Acquisition Mode

Complete the following steps to put the module in acquisition mode.

  1. Configure an FPGA I/O Node with the Start channel of the module.
  2. Wire a Boolean constant set to TRUE to the Start input of the FPGA I/O Node to send a synchronization pulse to the module. The module starts acquiring data at the data rate you configure.

Reading Data from the Module

When the module starts acquiring data, you can use an FPGA I/O Node to read data from the module. You can connect the AI output of the FPGA I/O Node (or, for the NI 9770, the RF In/I or RF In/Q items) to various types of functions, including an FPGA Memory function or an FPGA FIFO function. If you read from multiple channels on the module, place the channels in the same FPGA I/O Node to ensure that the VI reads the data synchronously.

Because the module internally acquires data at a specified rate, the FPGA I/O Node does not return data until new data has been acquired by the module. If the module did not start acquiring data or stops acquiring data while an FPGA I/O Node is waiting for data from the module, the FPGA I/O Node returns I/O Not Start error 65582.

Exiting Acquisition Mode

Complete the following steps to exit acquisition mode.

  1. Configure an FPGA I/O Node with the Stop channel of the module.
  2. Write a TRUE to the Stop input. The module is no longer in acquisition mode and you can now access its properties or, for some modules, TEDS information.

Example

Refer to the module Getting Started (FPGA) VI at labview\examples\CompactRIO\Module Specific\<module>\<module> Getting Started for an example of reading from the module.

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