Category Archives: Sensors

Proximity (Capacitive, Inductive), Photo electric (Thru beam, Retro Reflective, Diffuse), Ultrasonic, etc. Sensors can be either discrete (On/Off) or Analog outputs.

Universal Signal Conditioner and Isolator

Signal conditioners are used with analog current and voltage signals. They have the ability to change your input analog signal to another output analog signal. As an example, we can have 4-20mA analog input and change it to a 0-10VDC output signal so we can wire this into our PLC. Typically signal conditioners will also electrically isolate the input and output signals. This is either done by magnetic or optical isolation. You would usually specify the input and output signals that are required in your circuit to choose the signal conditioner required. Using a universal signal conditioner will take a variety of signals and is a great product to use in troubleshooting analog circuits.

We will be using a universal signal conditioner to convert a thermocouple temperature input into a 0-10VDC linear output. This will be wired into the analog card of the Click PLC.
Let’s get started. Continue Reading!

Wiring an Ultrasonic Proximity Sensor to the Click PLC

An ultrasonic sensor (switch) is able to detect object presence without physical contact (limit switch). No physical contact means that the switch has no parts that will wear out. The life span of the sensor is increased with less maintenance.
An ultrasonic sensor will use sound waves to detect objects. These sound waves are at a level that we cannot hear. Distance is measured by the time it takes to send and receive the ultrasonic wave. Objects can be measured the same no matter what the colour, transparency, shininess, or lighting conditions of the application.

We will be wiring an ultrasonic sensor into the input of our Click PLC. This will include a discrete and analog input signal. The UK1F-E7-0A is an 18mm diameter sensor that has a PNP N.O./N.C. selectable output with analog output of 0 -10 VDC. The sensing distance is 200mm to 2200mm and has a one-hertz switching capacity. A 4-pin M12 quick disconnect is available but we will be wiring in our 2m wired version. Let’s get started. Continue Reading!

Wiring a Capacitive Proximity NPN PNP Sensor to the Click PLC

A proximity sensor (switch) is able to detect object presence without physical contact like a limit switch. No physical contact means that the switch has no parts that will wear out. The life span of the sensor is increased with less maintenance.
A capacitive proximity sensor will detect ferrous and non-ferrous objects. The sensor works by oscillating the charge on the plates in the sensor. When an object is placed in front of the surface, the amount of current flow is detected. (Capacitance) The dielectric of objects will determine the distance that the object can be detected.

We will be wiring a capacitive proximity switch into the input of our Click PLC. The CK1-00-2H is an 18mm diameter, NPN/PNP N.O./N.C. selectable output with a 12mm sensing distance. That means that the sensor can be wired as positive (Sourcing) or negative (Sinking) switch. This unshielded 10 Hz switching frequency sensor also has a 4-pin M12 quick disconnect. Let’s get started. Continue Reading!

Wiring an Inductive Proximity NPN PNP Sensor to the Click PLC

A proximity sensor (switch) is able to detect object presence without physical contact like a limit switch. No physical contact means that the switch has no parts that will wear out. The life span of the sensor is increased with less maintenance.
An inductive proximity sensor will detect ferrous metals. The sensor develops an electric field when metal (sensing object) is introduced usually killing the oscillation circuit of the sensor triggering the output.

We will be wiring an inductive proximity switch into the input of our Click PLC. The AM1-A0-4A is an extended range 12mm tubular sensor that can be wired into the PLC as a sink or source input. Let’s get started. Continue Reading!

ACC Automation 2017 Review

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We would like to take a few minutes and reflect on the past, current and future of ACC Automation. 2017 has been our best year yet thanks to you. Your questions, comments and suggestions have helped us to build the site that you see today.
Thank you. Continue Reading!

BRX PLC High Speed IO

The BRX series of programmable logic controllers has built in high speed inputs and outputs. Every CPU will have either 6 or 10 high speed inputs (HSI) available depending on the model. These inputs can be used for input frequencies from 0 to 250Khz. 250Khz represents 250000 input counts per second that can be coming from devices connected to your PLC like an encoder. Every BRX CPU unit also has 2, 4 or 8 high speed outputs (HSO) available depending on the model. The outputs can send a frequency of pulses out up to 250Khz. Due to the speed of the IO, these functions available on the BRX PLC will operate asynchronous with the PLC scan time.
We will be looking at sending an output of pulses at different frequencies from our BRX PLC and inputting these back into the high speed inputs of the PLC. So our output will be wired back into our input. We will then display the frequency of the input pulses and the count. As a system integrator, this ability to send and receive high speed inputs and outputs can prove very useful to you in the field when commissioning your automation system.
Let’s get started with the BRX PLC High Speed IO. Continue Reading!

Implementing the Solo Process Temperature Controller

The SOLO Temperature Controller is a single loop dual output process temperature controller that can control both heating and cooling simultaneously. It is available in 1/32, 1/16, 1/8 and 1/4 DIN panel sizes and is UL, CUL and CE approved. The name of temperature controller is deceiving. This unit will also accept voltage and current into them, which is great for process control.

Recently I was asked: How you can change the pressure value from PSI to Bar?

They were bringing into the controller a voltage signal. This can be scaled using the tP-H (High level signal) and tP-L (Low level signal). The units on the display scaled for you. The default is -999 to 999. See section 11-2 of the following information guide that comes with the controller. Continue Reading!

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 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!

The 7 Essential Parts of a PLC System

When I was in school PLC’s were just in their infancy. We were taught that the PLC consisted of the central processing unit (CPU), analog and digital inputs and outputs. Everything was programmed with dedicated handheld devices and/or software devices on specialized hardware. We now have modern PLC systems that are capable of so much more. Let’s look at how we can now break up these modern PLC system into the seven essential components.

CPU
Inputs and Outputs (I/O)
Analog I/O
Specialty I/O
Programming Tools
HMI
Networking Continue Reading…

PLC Programming Example – Paint Spraying

We will look at a PLC basic tutorial of a paint spraying station. Following the 5 steps to program development this PLC programming example should fully explain the procedure for developing the PLC program logic. Ladder will be our PLC programming language.


We will be using the Do-more Designer software which comes with a simulator. This fully functional program is offered free of charge at automation direct.

Define the task:

What has to happen?
Paint Station 01

Paint spraying system where boxes are fed by gravity through a feeder magazine one at a time onto a moving conveyor belt. Upon the start signal, boxes are pushed towards the conveyor by valve 1. This is a cylinder which extends and retracts which operates switches S1 and S2 respectfully. A spraying nozzle paints each box as it passes under the paint spray controlled by valve 2. A sensor (S3) counts each box being sprayed. When 6 boxes have been painted the valve 2 shuts off (paint spray) and valve 1 (cylinder) stops moving boxes onto the conveyor. Three seconds later the conveyor stops moving and the hopper with its load moves forward (valve 3) where it is emptied. Ten seconds later the hopper returns to the original position. The cycle is then complete and waits for a start signal again.

Define the Inputs and Outputs:

Inputs:
Start Switch – On/Off (Normally Open) – NO
Stop Switch – On/Off (Normally Closed) – NC
S1 – Valve 1 (cylinder retract) On/Off – NO
S2 – Valve 1 (cylinder extend) On/Off – NO
S3 – Box Detected- On/Off – NO
Outputs:
Motor – On/Off (Conveyor Run)
Valve 1- Cylinder to feed boxes – On/Off
Valve 2- Paint Spray – On/Off
Valve 3- Cylinder to move hopper – On/Off

Develop a logical sequence of operation:

Fully understanding the logic before starting to program can save you time and frustration.

Sequence Table: The following is a sequence table for our paint spraying application.

Sequence Table
1 – Input / Ouput ON
0 – Input / Output OFF
x – Input / Output Does not Matter
When the power goes off and comes on the sequence will continue. This means that we must use memory retentive areas of the PLC. The stop pushbutton will stop the sequence. The start will resume until the end.

Develop the PLC program:

The best way to see the development of the programmable logic controller program is to follow the sequence table along with the following program. You will see the direct correlation between the two and get a good understanding of the process.

This is the main process to start and stop bit. V0:0 is used because it is memory retentive.
Paint Stn Program 1

Control of the Motor (Conveyor) and the paint spray is done with the V0:0 contacts in front of the actual PLC output. The conveyor and paint spray will stop when the timer 0 is done. This is the delay after the last box is detected to allow the box to be painted and loaded onto the hopper.
Paint Stn Program 2

Control of the box movement onto the conveyor. As long as we have the process start and the hopper count is not complete this will allow the cylinder to put boxes on the conveyor.
Paint Stn Program 3

Count number of boxes in the hopper via S3. The counter is memory retentive.
Paint Stn Program 4

A timer to stop the conveyor and spray after the last box is detected for the hopper. This will allow time for the box to be sprayed and loaded into the hopper.
Paint Stn Program 5

Hopper movement to load and unload the boxes.
Paint Stn Program 6

The hopper unload timer is to unload the boxes and will then trigger the reset conveyor timer, box counter and the process start bit (V0:0).
Paint Stn Program 7

Test the program:

Paint Spraying
Test the program with a simulator or actual machine. Make modifications as necessary. Remember to follow up after a time frame to see if any problems arise that need to be addressed with the program.

Watch on YouTube: PLC Programming Example – Paint Spraying
If you have any questions or need further information please contact me.
Thank you,
Garry



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