Measurement Computing USB-231 - Manual (Page 24)

USB-231 User's Guide Specifications
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Digital input
Table 5. Digital input specifications
Parameter Condition Specification
Input voltage range Power on 0 V to 5 V
Power off 0 V to 3.3 V (Note 1)
Input voltage protection ±20 V on two lines per port (maximum of five
lines for all ports) for up to 24 hours
Input high voltage 2.3 V min
Input low voltage 0.8 V max
Input leakage current At 3.3 V 0.8 mA max
At 5 V 4.5 mA max
Note 1: Do not leave a voltage above 3.3 V connected on the DIO line when the device is not powered. This
can cause long-term reliability issues.
Digital output
Table 6. Digital output specifications
Parameter Condition Specification
Output low voltage 4 mA 0.7 V max
1 mA 0.2 V max
Output high voltage 4 mA 2.1 V min
1 mA 2.8 V min
3.6 V max
Maximum output current per
line ±4 mA
External digital trigger
Table 6. External digital trigger specifications
Parameter Specification
Trigger source TRIG input
Trigger mode Software configurable for rising or falling edge. Power on default is rising edge.
Input high voltage 2.3 V min
Input low voltage 0.8 V max
Counter
Table 7. Counter specifications
Parameter Specification
Pin name CTR
Number of counters 1
Resolution 32 bits
Counter type Edge counter, rising or falling
Counter direction Count up
Counter source CTR
Input frequency 5 MHz max
High pulse width 100 ns min
Low pulse width 100 ns min