Question

How do I determine which type of proximity sensor output I need, NPN or PNP?

Answer

PNP sensors are current sourcing devices and NPN sensors are current sinking devices.
A current sourcing sensor must be connected to a current sinking input. Likewise, a current sinking sensor must be connected to a current sourcing input, so you must know the input circuitry of the device you are connecting with the sensor.
Most AutomationDirect PLC input modules (except 305 series) allow NPN or PNP sensors to be connected. This is sometimes determined by what other type of devices are being connected to the PLC module.

---

FAQ Subcategory: None

This item was last updated on 2007-11-30
Document ID: 459

---

The information provided in the AutomationDirect knowledge base is provided "as is" without warranty of any kind. AutomationDirect disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall AutomationDirect or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if AutomationDirect or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion of limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.