Counter I/O Terminals - Measurement Computing USB-1208HS-4AO User Manual

USB-1208HS-4AO User's Guide
For more information on digital signal connections
For general information regarding digital signal connections and digital I/O techniques, refer to the Guide to
Signal Connections (available on our web site at www.mccdaq.com/signals/signals.pdf).

Counter I/O terminals

The terminals provide connections to each 32-bit counter input channel (
count frequencies of up to 20 MHz.
Timer output terminal
Use the terminal to connect to the pulse width modulation (PWM) timer output.
TMR
You can set the following timer output parameters through software:

pulse frequency

duty cycle (pulse width divided by the pulse period)

number of pulses to generate

time delay before starting the timer output after it's enabled

resting state of the output (idle high or idle low)
The timer can generate a pulse output with a programmable frequency range of 0.00931 Hz up to 20 MHz.
Both the period and time delay ranges are 50 ns to 107.4 seconds.
Trigger input terminal
The TRIG connection is an external digital trigger input. The trigger mode is software selectable for:

Level-sensitive or edge-sensitive

Rising or falling edge

High or low level
The default setting at power up is edge sensitive, rising edge.
Retrigger
The acquisition uses the trigger settings for positive edge/negative edge and level-sensitive/edge-sensitive, but
automatically re-arms the trigger after it is activated
Figure 11. USB-1208HS-4AO PWM timer channel
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Functional Details
CTR0 and CTR1) . Each counter can