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•
The channel is high impedance when the channel is turned off (1).
•
When driving inductive loads, use an external flyback diode or snubber circuit as shown in
Figure 19.
Figure 19. Connecting a Device to the NI WSN-3226 in Drive Low (Sinking) Mode
3V TTL Logic (Open-Collector with Pull-Up)
The 3V TTL Logic (Open-Collector with Pull-Up) mode can be used to connect to 3 V and 5 V logic
inputs with TTL Logic compatible thresholds. When using this mode:
•
The DIOx terminal is pulled-up to 3 V through a pull-up resistor for a DIO output value of 1 and
driven low to ground for a DIO output value 0.
•
The DIO line is read with 3V TTL Logic input thresholds.
•
A supply voltage is not required on DIO PWR.
NI WSN-3226
Drive High and Low (Sinking and Sourcing)
When using Drive High and Low (Sinking and Sourcing) mode:
•
Connect the device to DIOx and connect the device common to the DGND terminal corresponding
to that DIOx terminal.
NI WSN-3226 User Guide and Specifications
DI
(Internal)
Low Side Switch
NI WSN-3226
3 V
TTL
Pull Up
DI
(Internal)
Low Side
Switch
Figure 20. Connecting a Device to the NI WSN-3226 in 3V TTL Logic Mode
Flyback Diode
DIOx
Device
DGND
DIOx
TTL Device
DGND
22
+
External
Power
–
Supply
+
External
Power
Supply
–
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