Generation Considerations for DDR

DDR generation has some additional considerations for your application. The following diagram shows how digital data is stored in Generation Onboard Memory and how that impacts the trigger, event, and waveform quantum and the generated data.

Data Width

Data width is a function of your data rate multiplier. Since data width refers to how large your sample is in bytes, using DDR mode effectively halves your allowable data width. For example, on a device with 16 channels, you can generate or acquire data on all 16 channels. For the same device in DDR mode, you can generate on only eight channels and acquire on the other eight.

Memory Usage

Memory usage is effectively doubled per channel since the data width and channel count are halved.

Marker Positions

Marker positions have a quantization twice that of SDR mode. Refer to your device specifications for more information about quantization.

Waveform Sizes

The size of the waveforms you save to the onboard memory have a quantization twice that of SDR mode. Refer to your device specifications for more information about quantization.

Initial/Idle States

If a channel's Idle state is configured for "hold last value" (X), the last value held is the last DDR data sample.