Tag Archives: plc basics programming

BRX PLC Analog Dusk to Dawn Program

A dusk to dawn sensor usually is discrete on/off of the lighting control. If we want to vary the lights to mimic more of the sunset and rise, we would use an analog output to control the lights. I was recently asked about such a program. Every day they wanted the lights to go off at 10 pm and come back on at 6 am. At 9:30 pm the lights would be on at 70% or 7volts of a 0-10V signal. In the next half hour, the program will bring the lights from 70% down to 0%. In the morning the lights will come back on within the half-hour from 0% to 70%. Poultry Farms are one place that would utilize this program.

We will be developing a program that will do this with our BRX PLC (Do-More). Let’s get started! Continue Reading!

BRX PLC HTTP JSON Instructions

One of the features of the BRX Series PLC is the ability to expand its capability to fit your application. Software and hardware changes are ongoing so the PLC can grow with your needs. Communication is something that the BRX PLC can do very well. As part of the internet of things (IoT), the BRX will share and exchange data. You can also refer to this as the industrial internet of things. This will suit several industrial applications.

The Do-more Updates Release 2.5.2 on April 22, 2019, has introduced new instructions. Here are the instructions that we will be using:
HTTPCMD – HTTP Request / Response with Server (BRX only)
JSONPARSE – Parse JSON Text (BRX only)
We will be using these instructions to read the weather conditions from a website. Let’s get started. Continue Reading!

Productivity 1000 Series PLC PID Ramp Soak Instruction

PID Ramp Soak Instruction
The purpose of a ramp soak instruction is to make gradual, controlled changes in temperature (Ramp), followed by a temperature hold (Soak) period.
We will be using our Proportional-Integral-Derivative PID Instruction that we looked at last time to apply the ramp/soak instruction.

Using the immersion heater in a cup of water to keep the temperature at a constant value, we will be adjusting the profile of the temperature as we increase the set point (Ramp) and hold that set point for a predetermined time. (Soak)

We will be modifying our existing program from our PID loop instruction. Let’s get started. Continue Reading!

Productivity 1000 Series PLC PID Instruction

PID Loop (PID) Instruction (Auto Tuning)
A Proportional-Integral-Derivative algorithm is a generic Control Loop feedback formula widely used in industrial control systems. A PID algorithm attempts to correct the Error between a measured process variable and the desired setpoint by calculating and then outputting a corrective action that can adjust the process accordingly and rapidly, to keep the Error to a minimum.

The following links will explain the PID instruction.
https://www.csimn.com/CSI_pages/PIDforDummies.html
http://www.ni.com/white-paper/3782/en/
https://en.wikipedia.org/wiki/PID_controller
We will be using an immersion heater in a cup of water to keep the temperature at a constant value. Using the Productivity Suite software we will perform an autotune on our PID instruction.

Our immersion heater will be controlled through a relay using time proportional control from our PID output. Let’s get started. Continue Reading!

Productivity 1000 Series PLC Firmware Update

Firmware is usually PLC operating system code that is written into a read only memory. The BIOS (Basic Input Output System) of a PC (personal computer) is a good example of firmware. It provides the low level interface between the hardware and software. The firmware for the productivity series of PLC’s must be downloaded separately from the programming software.

We will be updating our firmware of our Productivity 1000 PLC from 1.2.5.36 to the latest version 1.2.7.37. Let’s get started. Continue Reading!

Productivity 1000 Series PLC Modbus TCP Ethernet Communication

The productivity series of PLCs comes with 4 built-in communication ports for easy connectivity to your PC or various industrial networks. Ethernet protocols like Modbus TCP can be utilized with the RJ45 port on this PLC. Modbus TCP is an open (published) protocol that uses the Server (Master) / Client (Slave) architecture. It’s a very common protocol used in industrial automation controls.

We will be using the RJ45 (Ethernet) port to communicate to a Click PLC. Modbus TCP will be the protocol used on this Ethernet communication media. The Productivity 1000 PLC will be the server and the Click PLC will be the client. We will be creating a network between the two PLC units. A heartbeat will be used so if communications is lost, the server (slave) will know. The throughput time will be timed by using a small program in the Click PLC. You will soon see how the Productivity Series of PLC’s is the best way to handle communication to other devices. Let’s get started. Continue Reading!

Productivity 1000 Series PLC Modbus RTU Serial Communication

The productivity series of PLCs comes with 4 built-in communication ports for easy connectivity to your PC or various industrial networks. Serial protocols like Modbus RTU can be utilized with either the RS232 or RS485 ports on this PLC. Modbus RTU is an open (published) protocol that uses the Master / Slave architecture. It’s a very common protocol used in industrial automation controls.

We will be using the RS485 (2-wire) port to communicate to a Solo Process Temperature Controller. Modbus RTU will be the protocol used on this serial communication media. The PLC will be the master and the Solo process temperature controller will be the slave. You will soon see how the Productivity Series of PLC’s is the best way to handle communication to other devices. Let’s get started. Continue Reading!

Productivity 1000 Series PLC Web Server

The productivity series of PLCs has a built in web server. This web server function can make a non secure (HTTP) connection to the CPU. This is done with your browser. You can then view read only system tags and open, save or delete files stored on the micro SD drive.

Previously we stored data logged files on the USB (Micro SD) storage device. We will now start and configure the web server function. Look at the files from our data logger and view the system files available. Let’s get started. Continue Reading!

Productivity 1000 Series PLC Data Logger

The productivity series of PLCs has a built in data logger. This easy data logger will log up to 64 tag values on a USB (Micro SD) storage device connected to the CPU. The logs will be stored in CSV (Comma Separated Values) file format. Logging can be triggered by the rising edge transition of a Boolean tag (event) or configured to occur at regular intervals (scheduled).

A USB storage device should be normally connected if logging data. The CPU maintains an internal 73KB buffer for temporarily logging data while no USB storage device is present. Data in the buffer will not be retained through a power cycle. Let’s get started. Continue Reading!