The below equation is used to calculate the bandwidth requirements per Digital Pattern Instrument based on the vector rate and the effective transfer size of the capture waveform. The calculated bandwidth requirement can then be check against the Capture Waveform Bandwidth Limitations to confirm that the Digital Pattern Instrument can properly acquire the configured capture waveform at the specified vector rate.
The PXIe-6570 has a PCIe Gen2 x4 connection which has a theoretical bandwidth limitation of 2000 MB/s. However, around 1600 MB/s can practically be achieved. Additionally, the bandwidth limitations of the PXIe chassis and controller must be considered. See the specifications for the specific chassis and controller for more information.
Calculating Required Capture Bandwidth:
Required Capture Bandwidth per Digital Pattern Instrument = Vector Rate × Effective Transfer Size
Vector Rate (MHz)
- Inverse of the period at which vectors with the "capture" opcode execute.
Effective Transfer Size (bytes)
# of Sites
- Number of sites the capture waveform is used for.
# of Capture Pins per Site (bytes)
- Number of capture pins per site rounded up to 1, 2, or 4 bytes. Each pin is considered one bit. For example, 4 capture pins per site would be considered 4 bits which rounds up to 1 byte.
- Sample width specified in the Capture Waveform Configuration.