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National Instruments 79546-01 Multifunction I/O Device

Also known as the PCI-6255, the 79546-01 is a multifunction I/O device from National Instruments that is very flexible and intended to provide extensive data acquisition (DAQ) capabilities. Two 32-bit counters/timers, associated digital I/O, analog and digital triggering, and other functions are included. Many applications, such as research, design verification/testing, production test scenarios, and laboratory automation, are well suited for this device.

The 79546-01 has 80 analog input channels with 16-bit resolution, supporting a variety of input values including ±10V, ±5V, ±2.0V, ±1.0V, ±0.5V, ±0.2V, and ±0.1V. Users can adjust the input range for each channel via the Analog Inputs tab of the HIL Initialize VI, though all analog inputs must share the same range setting. The device also includes 2 analog output channels with 16-bit resolution, supporting output ranges of ±10V and ±5V. These outputs can be configured for specific voltage settings when the block diagram is either running or stopped, through the HIL Initialize VI's Analog Outputs tab.

The 79546-01 has a broad digital I/O configuration option due to its 24 bidirectional digital lines and analog capabilities. Digital I/O tab in the HIL Initialize VI allows direction settings to be controlled for each individual digital line, which can be configured as an input or output. When transitioning between operations, users can additionally predefine the starting and final digital output values.

The 79546-01 can accommodate non-quadrature, 1X, 2X, and 4X quadrature modes and supports 2 quadrature encoder inputs with 32-bit count values. On the other hand, encoder filtering is not supported. The adaptability of the PCI-6255 is demonstrated by the fact that the same counters used for encoder inputs may also be set up as PWM outputs. The 80 MHz counter timebase rate used by the PWM outputs allows them to function in multiple modes, such as duty cycle, frequency, or period. PWM signals with 0% or 100% duty cycles, as well as zero frequency, are not supported by the device. The PWM signal period and the counter timebase rate determine the permissible duty cycle range.