Measurement Computing USB-202-OEM - Manual (Page 16)

USB-202-OEM User's Guide Specifications
16
Digital input/output
Table 8. Digital input specifications
Parameter Specification
Digital type TTL
Number of I/O 8
Configuration Each bit may be configured as input (power on default) or output
Pull-up configuration The port has 47
kΩ resistors that may be configured as pull-up or pull-down with
an internal jumper. The factory configuration is pull-down.
Digital I/O transfer rate
(system-paced) 33 to 4000 port reads/writes per second typical, system dependent
Input low voltage threshold 0.8 V max
Input high voltage threshold 2.0 V min
Input voltage limits 5.5 V absolute max
–0.5 V absolute min
0 V recommended min
Output high voltage 4.4 V min (IOH = –50 µA)
3.76 V min (IOH = –24 mA)
Output low voltage 0.1 V max (IOL = 50 µA)
0.44 V max (IOL = 24 mA)
Output current ±24 mA max
External digital trigger
Table 9. External digital trigger specifications
Parameter Specification
Trigger source TRIG input
Trigger mode Software configurable for edge or level sensitive, rising or falling edge, high or low
level. Power on default is edge sensitive, rising edge.
Trigger latency 1 µs + 1 pacer clock cycle max
Trigger pulse width 125 ns min
Input type Schmitt trigger, 47 k
Ω pull-down to ground
Schmitt trigger hysteresis 1.01 V typ
0.6 V min
1.5 V max
Input high voltage threshold 2.43 V typ
1.9 V min
3.1 V max
Input low voltage threshold 1.42 V typ
1.0 V min
2.0 V max
Input voltage limits 5.5 V absolute max
–0.5 V absolute min
0 V recommended min