Chapter 5 Signal Connections
© National Instruments Corporation 5-13 NI 7350 User Manual
Wiring Concerns
For proper use of each ADC input channel, the analog signal should be a
floating source with the positive terminal connected to the channel input
and the negative terminal connected to analog input ground. Figure 5-4
shows a simplified schematic diagram of this connection.
Figure 5-4. Analog Input Connectivity
Other Motion I/O Connection
The NI 7350 controller provides the host +5 V signal, which is the internal
+5 V supply of the host computer. This signal is typically used to detect
when the host computer is powered on and to shut down external motion
system components when the host computer is powered off or disconnected
from the motion accessory.
Caution The host +5 V signal is limited and should not be used to power any external
devices, except those intended in the host bus monitor circuits on the UMI and drive
products.
Interfacing With Optocouplers
Many motor drive manufacturers offer opto-isolated inputs for
Step (CW)/Dir (CCW) and other motion control signals. The NI 7350 is
well-suited to drive most of these inputs directly when you connect the
controller output signal to the positive side of the optocoupler input and
connect the controller GND to the negative side of the optocoupler input.
This method works if the optocoupler is designed to work with a 5 V signal,
requires less than 16 mA, and the NI 7350 output is configured for Totem
Pole output mode. Figure 5-5 shows a typical optocoupler wiring example.

+

–

+

–

V
s
Analog Input
Analog Input
Ground