National Instruments NI 7350 - page 49

Chapter 5 Signal Connections
NI 7350 User Manual 5-14 ni.com
Figure 5-5. Typical Optocoupler Wiring (Totem Pole Output Mode)
In some rare circumstances, the optocoupler will not work with a 5 V
signal, or it requires more current than the maximum current level the
controller can provide. In this case, connect the controller output to the
negative side of the optocoupler input, connect the positive side of the input
to a supply as specified by the drive manufacturer, and configure the
controller output for Open Collector mode. Figure 5-6 shows this special
case wiring example.
Figure 5-6. Special Case Optocoupler Wiring (Open-Collector Output Mode)
Caution If the optocoupler input does not include its own current-limiting resistor, you
must provide an external resistor in series with the NI 7350 output. To prevent damage to
the NI 7350 controller or other motion hardware, use a resistor that limits the current to a
value below the maximum specifications of the controller and other hardware.
+5
3.3 kΩ
7350 or UMI
STEP OUT
Drive
Step +
GND Step –
Optional
+5
3.3 kΩ
7350 or UMI
STEP OUT
Drive
Step +
Step –
VISO per
Drive Spec
Optional