I recently received a question on PNP and NPN sensors. They wanted an explanation of what a sink is and how to wire one. Confusion over the Normally Open and Normally Closed function of the sensor is also a common question. Several diagrams will show a resistor attached to the blue wire and a load across the others, what does it all mean?
It is quite confusing sometimes the language we use for these devices. Sometimes it is the way we talk about the sensor and sometimes about the device we are connecting. (PLC)
We will break it down and go over the wiring to a PLC input. Let’s get started. Continue Reading!
A push button (pushbutton) is a simple human interface for controlling some aspect of a machine or process. The push button requires a force to push the button to change the electrical operation from off to on or vice versa. The condition of the output is usually momentarily. Some common everyday pushbuttons we use are keyboards keys.
A selector switch is also a mechanical device that will require a force to turn the electrical operation from off to on or vice versa. The selector switch usually locks into a position.
We will be wiring two illuminated pushbutton switches into our Click PLC. A selector switch will also be wired in. Let’s get started. Continue Reading!
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 are in the mega ohm range where current input is typically 250 ohms. Our tester will be for analog voltage inputs (0-10 VDC). Check your input specifications before wiring anything to your PLC. I have used this tester for other voltage inputs along with a meter to ensure that the voltage levels do not get out of range for the input signal.
Analog inputs to the PLC are continuous and can come in a variety of signals. These signals can come from temperature, flow rate, pressure, distance, etc. Continue Reading!
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 connect our inputs and outputs on our programmable logic controller. (PLC) Continue Reading!