Wiring NPN, Sinking, Open collector Limit Sensors

[corvette]

I have a NI-Motion Controller (NI-PCI-7342) connected to a third part drive/motor. The End of Travel Sensors are NPN, Sinking, Open collector, Normally Closed, and the home sensor is similar only Normally Open. I want to wire these into the UMI-7764. The Manual for the Linear Table states:

Limit Sensor / Home Sensor Electrical Connections
LIMIT/HOME WIRING COLORS
+VDC - Brown
Ground - Blue
Signal - Black

I believe the +VDC (Brown) and the Ground (Blue) get connected to a 5V Power source. That leaves me the Signal (Black). Do I wire this into the corresponding Limit Switch locations in the UMI?

Thanks in Advance.

[MarcoPolo5]

Nick,

If your limit switches are sinking, you would need to have the "signal" wire connected to the limit input - which would sink the signal to ground.

The limit inputs have pullup resistor to pull them high - so if nothing is connected to the limit input, the signal will be high. A switch is used to pull it low by sinking to ground.

If your limit switches are normally closed, you will have to set the polarity in Measurement and Automation Explorer (MAX) to active-high - since the signal is always pulled low until the limit is reached which will open the circuit and cause the line to be pulled high by the pullup resistors. In this case, a high signal = active.

If the home switch is normally open, then polarity in MAX would be active-low.

See the UMI-7764 Users Guide figure 7 (page 😎 for Limit and Home switch connection

Hopefully that explains the connections better.

[Buechsenschuetz]

I think most of your questions have been answered already. If you are using a separate power supply for your limit/home switches (as it is suggested, since the 'host 5vdc output' of the 7344 controllers is NOT designed to be used as power supply) you have to connect the GND terminal of the power supply to one of the digital GND terminals of the UMI box. Otherwise your setup will not work.

Of course you can use the same power supply for both UMI box and limit/home switches, in this case you don't need a separate GND connection.