NI cDAQ-9174 - Counter n A, Counter n B, and Counter n Z Signals; Counter n HW Arm Signal

© National Instruments Corporation 61 NI cDAQ-9178/9174 User Guide and Specifications
• DO Sample Clock (do/SampleClock)
• Change Detection Event
• Analog Comparison Event
In addition, a counter’s Internal Output or Source can be routed to a different counter’s gate.
Some of these options may not be available in some driver software.
Routing Counter n Gate to an Output Terminal
You can route Counter n Gate out to any PFI terminal.
Counter n Aux Signal
The Counter n Aux signal indicates the first edge in a two-signal edge-separation measurement.
Routing a Signal to Counter n Aux
Each counter has independent input selectors for the Counter n Aux signal. Any of the following signals
can be routed to the Counter n Aux input:
• Any PFI terminal
• AI Reference Trigger (ai/ReferenceTrigger)
• AI Start Trigger (ai/StartTrigger)
• Analog Comparison Event
• Change Detection Event
In addition, a counter’s Internal Output, Gate or Source can be routed to a different counter’s Aux.
A counter’s own gate can also be routed to its Aux input.
Some of these options may not be available in some driver software.
Counter n A, Counter n B, and Counter n Z Signals
Counter n B can control the direction of counting in edge counting applications. Use the A, B, and
Z inputs to each counter when measuring quadrature encoders or measuring two pulse encoders.
Routing Signals to A, B, and Z Counter Inputs
Each counter has independent input selectors for each of the A, B, and Z inputs. Any of the following
signals can be routed to each input:
• Any PFI terminal
• Analog Comparison Event
Routing Counter n Z Signal to an Output Terminal
You can route Counter n Z out to any PFI terminal.
Counter n Up_Down Signal
Counter n Up_Down is another name for the Counter n B signal.
Counter n HW Arm Signal
The Counter n HW Arm signal enables a counter to begin an input or output function.
To begin any counter input or output function, you must first enable, or arm, the counter. In some
applications, such as a buffered edge count, the counter begins counting when it is armed. In other
applications, such as single pulse-width measurement, the counter begins waiting for the Gate signal
when it is armed. Counter output operations can use the arm signal in addition to a start trigger.