Ni usb-6001/6002/6003 User Guide National Instruments
• Software-Timed Generations
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Software-Timed Generations—Software controls the rate at which data is generated. Software sends a separate command to the hardware to initiate each NI DAQ conversion. In DAQmx, software-timed generations are referred to as on-demand timing. Software-timed generations are also referred to as immediate or static operations. They are typically used for writing a single value out, such as a constant DC voltage.
This signal is generated internally on your device. Hardware-timed generations have several advantages over software-timed acquisitions: – The time between samples can be much shorter. – The timing between samples can be deterministic. Hardware-timed operations are buffered. During hardware-timed AO generation, data is moved from a PC buffer to the onboard FIFO on the NI DAQ device using USB signal streams before it is written to the DACs one sample at a time. Buffered generations allow for fast transfer rates because data is moved in large blocks rather than one point at a time. One property of buffered I/O operations is the sample mode. The sample mode can be either finite or continuous: • Finite sample mode generation refers to the generation of a specific, predetermined number of data samples. After the specified number of samples is written out, the generation stops. • Continuous generation refers to the generation of an unspecified number of samples. Instead of generating a set number of data samples and stopping, a continuous generation continues until you stop the generation. AO Start Trigger You can configure PFI 1 or PFI 0 as the AO Start Trigger for analog output tasks. Refer to the Using PFI to Trigger an Analog Output Generation section for more information. NI USB-6001/6002/6003 User Guide | © National Instruments | 21 Digital I/O The NI USB-6001/6002/6003 has 13 digital lines: P0.<0..7>, P1. <0..3>, and P2.0. D GND is the ground-reference signal for digital I/O. You can individually program each line as input or output. All digital input and digital output updates and samples are software-timed. Figure 13 shows P0.<0..7> connected to example signals configured as digital inputs and digital outputs. You can configure P1.<0..3> and P2.0 similarly. tải về 1.5 Mb. Chia sẻ với bạn bè của bạn:
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