|Download Help (Windows Only)|
The NI 656x can be configured for single data rate (SDR) or double data rate (DDR) operation by setting the data rate multiplier for your acquisition and/or generation session in NI-HSDIO. The data rate multiplier can be independently configured for the generation and acquisition sessions.
When the data rate multiplier is configured for SDR operation, generation and acquisition sessions can run on all 16 channels of the NI 656x. Direction control is software-specified.
When the data rate multiplier is configured for DDR operation, the digital waveform generator/analyzer trades channel count for data rate by generating or acquiring on half the number of channels but at twice the rate. This rate is achieved by generating data on both the rising and falling edge of the Sample clock. For generation sessions, the device generates data on the lower eight channels of the NI 656x (DIO <0..7>), and for acquisition sessions the device acquires data on the upper eight channels (DIO <8..15>).
DDR mode has some important implications for some NI 656x functionality.