NI cDAQ-9172 User Guide and Specifications 58 ni.com
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. You can route the following signals to each input:
• Any PFI terminal
• Analog Comparison Event

Routing Counter n Z Signal to an Output Terminal

You can route Counter n Z to any output 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 buffered semi-period
measurement, the counter begins counting when 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.
Software can arm a counter or configure counters to be armed on a
hardware signal. Software calls this hardware signal the Arm Start Trigger.
Neutrally software routes the Arm Start Trigger to the Counter n HW Arm
input of the counter.

Routing Signals to Counter n HW Arm Input

You can route the following signals to the Counter n HW Arm input:
• Any PFI terminal
• ai/ReferenceTrigger
• ai/StartTrigger
• Analog Comparison Event