It's the number of bits in the digital code that generates the analog output. A larger number of bits reduces the magnitude of each output voltage increment, thereby making it possible to generate smoothly changing signals. Applications requiring a wide dynamic range with small incremental voltage changes in the analog output signal may need high-resolution voltage outputs. It's time to touch on both digital and analog triggering. Many DAQ applications need to start or stop a DAQ operation based on an external event.
Digital triggers synchronize the acquisition and voltage generation to an external digital pulse.
Analog triggers, used primarily in analog input operations, start or stop a DAQ operation when an input signal reaches a specified analog voltage level and slope polarity. National Instruments expertise in instrumentation led to the development of what's called Real-Time System Integration. The RTSI bus is included in NI's DAQ products. The RTSI bus uses a custom gate-array and a ribbon cable to route timing and trigger signals between multiple functions on one DAQ board, or between two or more boards. For example, with RTSI, two analog input boards can capture data simultaneously while a third board generates an output pattern synchronized to the sampling rate of the inputs.