Programmable Controller Basics Sourcing And Sinking Micro Logix

Programmable Controller Basics Sourcing And Sinking Micro. Logix Packaged Controllers

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.

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.

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

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

SOURCING vs. SINKING DC Inputs SINKING (NPN) SOURCING (PNP) Field Device + IN 1 DC Input Module DC Power Supply - +VDC DC COM + DC Power Supply - DC Input Module Field Device IN 1

SOURCING vs. SINKING DC Outputs SINKING (NPN) SOURCING (PNP) +VDC OUT 1 DC Output Module + Field Device DC Output Module + DC Power Supply - DC Power Supply Field Device OUT 1 DC COM

Rules 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.