Tag Archives: plc ethernet communication

BRX Do-More PLC to Stride Field IO Modbus TCP

The BRX Do-More PLC can use remote inputs and outputs from Stride. The Stride Field I/O Modules are simple and compact. They provide an economical means to connect inputs and outputs to an Ethernet Modbus TCP communication network. Every module operates as a standalone Modbus TCP server and can be configured via a built-in web server.
Previously we looked at the Stride Field Remote IO Modules Modbus TCP Ethernet wiring and configuration.
Stride Field Remote IO Modules Modbus TCP Ethernet
Unboxing SIO MB12CDR and SIO MB04ADS Video
Powering and Configuring Video
We will be connecting two Stride remote inputs and outputs to the BRX Do-More PLC. Modbus TCP will be the protocol over Ethernet to communicate to the SIO-MB12CDR and SIO-MB04ADS units.

SIO-MB12CDR
– STRIDE discrete combo module, Input: 8-point, 12-24 VDC, sinking, Output: 4-point, relay, (4) Form C (SPDT) relays, 2A/point, (1) Ethernet (RJ45) port(s), Modbus TCP server.
SIO-MB04ADS
– STRIDE analog input module, 4-channel, current/voltage, 16-bit, isolated, input current signal range(s) of +/- 20 mA, input voltage signal range(s) of +/- 10 VDC, (1) Ethernet (RJ45) port(s), Modbus TCP server.
We will be reading an analog voltage into the BRX Do-More PLC from the remote IO unit. We will then set an output to pulse on and off at a time range indicated by this analog signal. The output will be on the other remote IO unit and will trigger the input to signal. We will look at the Frequency, Count, and Status of this input. Our BRX Do-More PLC program will also take into consideration watchdog (communication time out) and power-up events for the Stride remote input and output units.
Let’s get started. Continue Reading!

BRX Do-More PLC MQTT Communications

MQTT stands for Message Queuing Telemetry Transport. This simple publish and subscribe communication protocol does not take too many resources.
Constrained devices with low bandwidth are ideal for MQTT. This protocol provides machine to machine (M2M) connectivity which is ideal for the Internet of Things. (IoT) This protocol is not for remote IO or real-time (deterministic) applications. MQTT is a good solution for applications that move data from hundreds or thousands of machines (sensors) to clients in many networks.

We will be installing a windows based broker called Mosquitto. The Do-More BRX PLC will be one of the clients publishing and subscribing to the MQTT broker. MQTT Lens (Chrome Browser App) will be the other client publishing and subscribing to the MQTT broker. Each client will share information. Let’s get started. Continue Reading!

BRX Do-More Simulator MQTT Publish Subscribe

MQTT stands for Message Queuing Telemetry Transport. It is a simple publish and subscribe communication protocol that does not take too many resources.
Constrained devices with low bandwidth are ideal for MQTT. This protocol provides machine to machine (M2M) connectivity which is ideal for the Internet of Things (IoT) or Industrial Internet of Things. (IIoT)

We will be using a free on-line public MQTT broker from HiveMQ. Messages will be published and subscribed to by two clients. The first will be an MQTT Browser Client by HiveMQ. The Do-More Designer Simulator PLC will be the second MQTT Client. Information in the form of bits and words will be published and sent to both clients. Let’s get started. Continue Reading!

BRX PLC PID Ramp Soak Profile

The purpose of a ramp soak profile 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 with PWM output that we looked at last time to apply the ramp/soak profile.
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 setpoint (Ramp) and hold that set point for a predetermined time. (Soak) We will then decrease that temperature back to the original setting. (Ramp)

We will be modifying our existing program from our PID with PWM Output post. Let’s get started. Continue Reading!

BRX PLC PID with PWM Output

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.

Here are some references on PID control:
PID without a Ph.D. By Tim Wescott
Understanding PID in 4 minutes
PID Control – A brief introduction
PID Controllers Explained
Who Else Wants to Learn about On-Off and PID Control?
We will be using an immersion heater in a cup of water to keep the temperature at a constant value. Using the Do-More Designer 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!

BRX PLC INC DEC 512 Registers for DMX512

I was recently asked the following question after posting the Analog Dust to Dawn program:
” I was wondering if there’s an easy way to increment and decrement a range of values.
e.g. I have a range of registers (V100 ~V611) the values in each register are different. But I want to increment or decrement all the registers values by 1 at the same time. So that the ramp rate is the same.
Is that possible without having to do 6 rungs of logic for each register?
To elaborate a little on my use case. 512 registers were chosen because that equals one DMX universe. So my scaling factor is 0~255.
16 channels are mapped to two BX-08DA-2B modules to control 0-10 fixtures. All other channels are mapped to SERIO module to control DMX512 fixtures and other devices.”

We will be looking at the DMX512 protocol and how to control 512 registers at a time using our BRX PLC (Do-More). Let’s get started! Continue Reading!

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!

Modbus RTU BRX PLC Master to Click PLC Slave Communication

Recently I was asked to demonstrate communication between a BRX PLC and Click PLC using Modbus RTU. Both PLCs are available from automation direct com. Modbus serial communication (Modbus RTU) is a standard protocol used in many automation devices. It works on a Master / Slave configuration. You can have only one master per network on Modbus RTU (Remote Terminal Unit). A maximum of 32 devices (Nodes) on the network can communicate to the master. A review of the Modbus RTU protocol (RTU frames) can be seen at the following URL.
http://www.rtautomation.com/technologies/modbus-rtu/
Using the BRX PLC as a Master, we will be communicating to the Click PLC (Slave). Our example will read 10 registers from the Click PLC and write 10 registers from the BRX PLC. Let’s get started! Continue Reading!

BRX PLC Online Editing and Debug Mode

Our first program for the BRX PLC involved a start stop jog circuit. We will now use the Do-More Designer Software to modify this program while the PLC is scanning the logic. This is referred to as online programming or online editing. As a system integrator, this ability can prove very useful to you in the field when commissioning your automation system.
We will also be using the special Debug Mode of the software to monitor the ladder logic status and bits on a scan by scan basis. Forcing the inputs and outputs, we will control the execution of the PLC scan. This is a great feature of the Do-More Designer software.
Here is a link explaining the logic behind our circuit.
How to Make a Start Stop Jog Circuit in a PLC
Let’s get started. Continue Reading!