Create an Analog Voltage Input Tester for a PLC

Create an Analog Voltage Input Tester for a PLC

We will create a simple and inexpensive analog voltage tester for a PLC using a potentiometer and a 9VDC battery. The potentiometer will be 5K ohms. This should be enough impedance for most analog inputs of the programmable logic controller. (PLC) Voltage impedance for analog voltage inputs is in the megaohm range where the current … Read more

Wiring Interposing Relays – NPN PNP Isolation

Wiring Interposing Relays - NPN PNP Isolation

We will now look at wiring interposing relays to connect an NPN and PNP sensors into the PLC. Interposing relay means a device that will separate two different circuits. The isolation can be for current consumption, voltage differences, voltage references, or a combination of both current and voltage. We can use these relays to help … Read more

Here’s a Quick Way to Wire NPN and PNP devices

Here’s a Quick Way to Wire NPN and PNP devices I often get asked how to wire NPN and PNP devices to the programmable logic controller. This can be unclear at first when looking at the wiring diagrams. I have managed to destroy a few sensors in the process….. so let’s get started, and I … Read more