Category Archives: Scan

Scan of the PLC. Reading inputs, solving logic, setting outputs, communications, etc.

Productivity Open P1AM Industrial Arduino Time Instructions


Time instructions in our productivity blocks programming (Arduino sketches) consist of runtime (ms), runtime (us), delay ms, and delay microseconds us.

We will be looking at each of these instructions that are available for our program using productivity blocks. Delay instructions in our sketches should be used with caution. They will pause our program for the delayed time, not allowing other parts of the program to function. We will be looking at this and the method to do the exact same delay functions without pausing your program.

A sample program will be discussed to demonstrate the time functions in our program. Let’s get started. Continue Reading!

Productivity Open P1AM Industrial Arduino Program Control

Arduino programs (sketches) can be written in thousands of different ways. The best way will determine the purpose of your program and what you are trying to accomplish. To simplify the logic we will be looking at program control that can be achieved using productivity blocks.
Program control will look at subroutines (sometimes referred to as methods or functions), conditional statements and looping statements. These three items can be combined to reduce your code length, make your program easier to read, and in turn easier to troubleshoot.

We will be looking at each of these instructions that are available using productivity blocks. A sample program will then be discussed that will contain some program control as a demonstration. Let’s get started. Continue Reading!

BRX Do-More PLC Ethernet Remote IO Controller BX-DMIO

The BRX Do-More PLC has its own line of remote input and output expansion units. You can add up to 8 I/O expansion units per controller (CPU) and 8 BRX expansion modules per expansion unit. This will make your system grow with your needs.

The remote I/O expansion units feature the following:
• All units have built-in Ethernet port, 10/100 Mbps
• MBIO units have onboard RS-485 port with removable 3-Pin connector
• Support for 8 expansion modules
• AC and DC powered units available
• AC powered units include an integral 24VDC auxiliary output power supply
• Power connector and serial port connector included

We will be looking at the BX-DMIO-M. This is the Do-More Ethernet Remote I/O supported protocol unit. We will discuss the hardware and then connect and configure the unit to work with our existing BRX Do-more PLC. Let’s get started. Continue Reading!

Productivity Open P1AM Industrial Arduino Serial Monitor COM

The Arduino integrated development environment (IDE) has a built-in pop-up serial monitor. The serial monitor can be used to receive and send serial data to our Arduino program. This can be a great feature to help us in debugging or controlling Arduino programs. (Sketches)
We will be modifying the blinking light program that we did previously and add a one to an integer every time the P1AM-100 arduino CPU switch is on. This will be then printed on the serial monitor.

Removing the blinking light, we will run our program again an see the difference in speed with the delay instructions removed. Productivity blocks will be used to program our industrial arduino controller.
We will then look at escape character codes that we can use with our industrial arduino. Since the built-in serial monitor will not interpret the escape codes, we will be using Putty as our serial monitor program. Let’s get started. Continue Reading!

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!

Productivity 1000 PLC to Stride Field IO Modbus TCP

The Productivity Series of 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 P1000 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 Productivity 1000 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 Productivity 10000 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. Keep on Reading!

Omron CP1H Program Control Instructions

The Omron CP1H programmable logic controller has several different ways to control the program and the way in which your program executes. Sequence control, Subroutines, and Step instructions can be used. These are just a few ways in which the controller will execute your logic using a synchronous PLC scan. Understanding the PLC program scan will explain the synchronous and asynchronous program scanning.
Interlocks, Jumps, For Next Loops, Subroutines and Step instructions are some of the ways in which we can control our program in the PLC. We will be looking at some of these instructions in the Omron CP1H PLC. Examples of some of the instructions will be presented. Continue Reading!

Who Else Wants To Know How A PLC Scans?

Programmable Logic Controllers (PLC) will scan very quickly. This can be anywhere from 1 to 20 ms, which translates into 1000 to 500 times each second. But what exactly is a scan?

A scan is when the PLC will complete the following:



Read Inputs:
Look at all of the inputs to the programmable controller. Digital, Analog, Communication
Execute Program:
Solve the logic to determine the output status. PLCs generally will solve the logic from left to right, top to bottom. The output of the rung before is available for the next rung.
This is like some of the popular bands of PLCs like MitsubishiAllen Bradley, Siemens, Omron, Automation Direct, etc. There are some exceptions like older Modicon models which solve the logic top to bottom, left to right. Always refer to the manufactures manual to ensure the program execution method.
Diagnostics and Communication:
The PLC will do a self check. It will verify that no errors exists in memory, cards attached, etc. This is critical because the PLC in an industrial application can have devastating effects if something malfunctions and the machine continues to function erratically. The PLC will stop executing, return the outputs to a normal state and indicate an error has occurred.
Communication will happen to the remote I/O, operator panels, etc.
Update Outputs:
Outputs are set according to the PLC program. (Digital, Analog) This is where the physical items will start moving. (Motors, Valves etc.)
To understand the scan, lets take a look at an example.
The following program will look at input X0 and set an internal bit for one scan one the rising edge of the input and one on the trailing edge of the input. The rising edge is when the input transitions from off to on and the trailing edge is when the input transitions from on to off.
The bits will only be on for one scan so we will increment an internal word by one when the bits go on. This way we will be able to see the bit increment in the word.
Leading edge one shot (one scan) bit. When the input signal goes on (X0) and C1 is not on, then C0 is turned on. The next rung will have C0 and X0 on so C1 turns on.
Remember: The PLC will scan from left to right, top to bottom and the outputs from the previous rung are available for the next.
C0 is on so the increment will add one to D0.
The next scan X0 is still on, C1 is now on so output C0 is turned off. C0 has been now on for one scan from the transition from off to on.
Trailing edge one shot (one scan) bit. When the input signal goes ooff (X0) and C3 is not on, then C2 is turned on. The next rung will have C2 and not X0 on so C3 turns on.
C2 is on so the increment will add one to D1.
The next scan X0 is still off, C3 is now on so output C2 is turned off. C2 has been now on for one scan from the transition from on to off.

Contact me for the above program. I will be happy to email it to you.
If you have any questions or need further information please contact me.
Thank you,
Garry

You can download the software and simulator free at the following address. Also listed are helpful guides to walk you through your first program.
Do-more Designer Software

How to use video’s for Do-more Designer Software




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