Waveforms Section

Waveforms allow users to view selected simulation signals at higher speeds and with better resolution than that offered by custom device channels. Custom device channels perform single-point acquisition, a non-buffered operation that occurs at the rate at which the Real-Time CPU runs. Waveforms, on the other hand, read and stream FPGA-generated data at rates faster than the Real-Time CPU.

Waveforms Configuration Page

In the System Explorer window configuration tree, expand the Power Electronics Add-On (OPAL-RT Circuit) custom device and select Circuit >> Waveforms to display this page.

The following mapping options are available at edit time:

Waveforms Section Channels

The Waveforms section of the Configuration Tree is populated with a list of Waveform channels corresponding to each of the 32 Waveforms available in the FPGA design. Use these tree items to display the mapped signals in Waveform Graphs in the VeriStand Workspace, or in Charts in the VeriStand Editor. More information about this process can be found in How to Display Simulated Signals using Waveforms.

To connect a measurement from the circuit to a given waveform channel, select any measurement and enable the Waveform destination.

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Waveform Data Transfer and Streaming Rate

As the simulation executes, data generated on the FPGA is sampled by the waveform engine at the user-specified Sample Rate, then streamed to one or more of the 32 Waveform channels on the real time CPU. Each individual channel is sampled at the full Sample Rate. Because the FPGA executes much faster than the acquisition rate of the waveform engine, the data is first decimated on the FPGA and subsequently stored in an FPGA FIFO. The values stored in the FIFO are transferred over the PXI backplane to a real time buffer on the CPU, then to the VeriStand Waveform channels. All data transfer occurring after the FPGA decimation is lossless.

The maximum achievable Waveform Sample Rate is dependent upon the characteristics of the system, although rates of up to 290,000 Samples/second have been achieved in all supported versions of VeriStand. The number of configured Waveform mappings does not affect the maximum achievable Sample Rate; all 32 Waveform channels are transferred at all times, even if they have not been mapped to a Source.

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Related Links

How to Display Simulated Signals using Waveforms

How to Log Waveform Data to a File