1. MicroLogix Packaged Controllers Programmable Controller Basics Sourcing And Sinking

2. Sourcing/Sinking Basics A transistor is a solid-state switch. Typically, dc modules are available that will work with 5, 12, 24, and 48 volts. Don't mix NPN (sinking) and PNP (sourcing) devices on the same module NPN (sinking) type sensor has the load switched to ground PNP (sourcing) type sensor has the load switched to positive voltage.

3. Sourcing/Sinking Basics Common types available are BJT and MOSFET. –BJT (Bipolar Junction Transistor) less switching capacity faster switching time –MOS-FET (Metal Oxide Semiconductor- Field Effect Transistor). Higher current capacity Slower switching time Check the specifications of the particular PLC you are going to use and never exceed the manufacturers maximum switching current.

4. SOURCING vs. SINKING DC Power Supply + - DC COM +VDC

5. SOURCING vs. SINKING +VDC SOURCING Pushbutton (PNP) SINKING Pushbutton (NPN) DC Power Supply + - DC COM DC Power Supply + -

6. SOURCING vs. SINKING DC Inputs DC Power Supply Field Device DC Input Module + - DC COM IN1 DC Input Module Field Device DC Power Supply + - +VDC IN1 SOURCING (PNP) SINKING (NPN)

7. SOURCING vs. SINKING DC Outputs DC Power Supply Field Device DC Output Module + - DC COM +VDC OUT1 DC Power Supply Field Device DC Output Module + - DC COM +VDC OUT1 SOURCING (PNP) SINKING (NPN)

8. Rules Field devices on the positive side (+VDC) of the field power supply are sourcing field devices. Field devices on the negative side (DC COM) of the field power supply are sinking field devices. Sourcing field devices must be connected to sinking I/O cards and vice versa. Sinking field devices must be connected to sourcing I/O cards and vice versa. RULES