Inst ToolsInst ToolsInst Tools
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Search
  • Books
  • Software
  • Projects
  • Process
  • Tools
  • Basics
  • Formula
  • Power Plant
  • Root Cause Analysis
  • Electrical Basics
  • Animation
  • Standards
  • 4-20 mA Course
  • Siemens PLC Course
Reading: Distributed IO Sharing Between PLC Systems – Technical Insights
Share
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • Design
  • PLC
  • Interview
  • Control System
Search
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > PLC Tutorials > Distributed IO Sharing Between PLC Systems – Technical Insights

Distributed IO Sharing Between PLC Systems – Technical Insights

Learn how to do Distributed IO sharing between PLC systems. Gain expert insights for advanced industrial automation solutions.

Last updated: December 15, 2023 5:22 pm
Mahmoud Salama
PLC Tutorials
No Comments
Share
10 Min Read
SHARE

In previous articles, we introduced the concept of distributed IO modules, and how to configure an IO module with a PLC. In this article, we will show how to do Distributed IO Sharing Between PLC Systems.

Contents
Problem descriptionDistributed IO Sharing Between PLC SystemsSharing the IO device with two PLCsAssigning different internal modules to PLCs

Contents:

  • Problem description.
  • Sharing the IO device with two PLCs.
  • Assigning different internal modules to PLCs.

Problem description

In the previous article, we showed how we can connect and configure a distributed IO module with a PLC and control the IO points of the Distributed module through that PLC. In this article, we discuss the case when we need to use the same distributed IO module with two different PLCs. See picture 1.

Sharing Distributed IOs between 2 PLCs

Picture 1. Two different PLC projects.

Distributed IO Sharing Between PLC Systems

Imagine that we need to share the inputs and outputs points of the distributed module between the two PLCs. Sharing a distributed IO module between two PLCs is possible but not all modules can do that, but most modern ones can.

Another way to share the information would be to get all the information from the distributed IO to one PLC and establish communication between the two PLCs and then exchange the needed data. This will be shown in another article.

In the distributed IO device (IO device_1) we have configured many IO modules such as 4DIx24VDC module, 8DOx24VDC module, 2DIx24VDC module, and some more modules. See picture 2.

Different IO modules in our IO device

picture 2. Different IO modules in our IO device.

Sharing the IO device with two PLCs

In this article, we will assume as you see from the picture that we want to control the 4DIx24VDC module and 8DOx24VDC module through PLC_1 and I want to control the 2DIx24VDC module and, 2DOx24VDC module from PLC_2.

So I want to share the different modules between the two PLCs, hence the name-sharing devices.

As you can see in picture 1, the distributed IO device (IO device_1) is already an extension of PLC_1as we set that up in the previous article, but we also need to make it an extension of PLC_2 so it can be shared between the two PLCs. See picture 3.

Sharing the IO device with two PLCs

picture 3. IO device is an extension of PLC_1

Usually, when doing that we would have each PLC on a different TIA Portal project, but as we don’t have real hardware devices, we will just use one TIA Portal software project to show how to share the distributed IO module between the two PLCs.

We have one project with two PLCs. And we need to assign the IO device_1to the PLC_1 and PLC_2

To do that, copy the module in the Network view and paste it to have two modules in your project. See picture 4.

Automation Control with Multiple PLCs

picture 4. Copy and paste the IO device.

Now, we need to assign this IO device to the PLC_2, as we did with PLC_1 in the last article. See picture 5.

PLC Interconnection

picture 5. Assign the module to PLC_2

NOW, if you try to download your project to both PLCs, the PLC_1 will be able to find the IO module. However, PLC_2 will not be able to find the IO module because there is no actual hardware module that is named IO device_2, we have only one hardware IO device and from last article it was configured with the name IO device_1 that is why the PLC_2 will not find the IO device. See picture 6.

Shared IO in PLC

picture 6. Connection is made through Device Network Name.

So, we need to give the same device network name to both IO modules, see picture 7.

PLC System Networking

picture 7. Network device name

As you can see, the Network Device Name for the IO module is IO device_1, see picture 8 for the other IO module.

Synchronized PLC Systems

picture 8. Network Device Name for the 2nd IO module.

Here, the network name is IO device_2. We need to give both IO modules the same name so both PLCs can find it and connect to it.

Unclick the automatic name generation option so we can change the name and make both of them IO device_1, also make sure that all information inside the red area is the same in both modules. See picture 9.

PLC-to-PLC Communication

picture 9. Unclick the automatic generation option.

Check pictures 10a and 10b after we changed the information to be the same for both modules.

Distributed IO Sharing Between PLC Systems

Picture 10a. 2nd IO module.

Sharing IOs on one remote IO station between more PLCs

Picture 10b. 1st IO module

Now that the two IO modules are identical, both PLCs can find and communicate with the IO module. See picture 11.

Sharing an input between two plc

picture 11. Both PLCs can find the IO module.

Up until this point, we were assuming that both PLCs are within the same TIA Portal project.

But, in case we are sharing the IO module with a controller in another TIA Portal project, we will do the same as before but we will add an extra step.

In this step, we will go to the properties of the IO module and change the shared device IO cycle option as you see in picture 12.

How do I communicate between two PLC CPU

picture 12. IO controller outside the project

As you can see from the picture, if the two PLCs are of different TIA Portal projects, we will change the value inside the red box to 1.

As we have both PLCs in the same project we will keep it zero.

Now that both PLCs can see and communicate with the IO device, we need to tell the IO module, which internal modules should communicate with which PLC.

As we mentioned in picture 2, we need a 4DIx24VDC module and 8DOx24VDC module to communicate withPLC_1 and I want to control the 2DIx24VDC module and 2DOx24VDC module from PLC_2.

We can do that by following the following steps.

Assigning different internal modules to PLCs

Start by going to the properties of the IO device_1, you will find that all internal modules of the IO device belong to PLC_1. See picture 13.

Assigning different internal modules to PLCs

picture 13. Shared device of the IO module.

As you can see from the picture, accessing all internal modules of the IO device is assigned to PLC_1, but as we mentioned before we need the last two internal modules 2DIx24VDC module and 2DOx24VDC module to be accessed by PLC_2.

To do so, just right-click the module you want and unselect the PLC_1 option, and make it blank to indicate that this module will be controlled through a different controller. See picture 14.

Sharing a Tag between two PLC

picture 14. Unselect internal modules.

If you check the device overview of the IO device_1 after you unselect the PLC_1 option, you will see that those internal modules have no addressing assigned with the PLC_1 indicating they belong somewhere else. See picture 15.

Sharing data between two PLC systems

picture 15. No addressing for modules not assigned to PLC_1

NOW, I need to assign those two modules to the IO device_2 for PLC_2.

By doing the same steps as before, go to the shared device properties of the IO device_2, and assign only the two needed modules with PLC_2. See picture 16.

How To Transfer Data Between Two PLCs

picture 16. Assign needed modules to PLC_2

Now that the 2DIx24VDC module and 2DOx24VDC module are assigned to PLC_2, if you check the device overview you will find their addressing with PLC_2 as we want. See picture 17.

Communication between PLCs

picture 17. Addressing belong to PLC_2

That is how we can share one IO module between two PLCs, whether they are in the same TIA Portal project or in two different projects.

If you liked this article, then please subscribe to our YouTube Channel for Instrumentation, Electrical, PLC, and SCADA video tutorials.

You can also follow us on Facebook and Twitter to receive daily updates.

Read Next:

  • PLC Sizes and Applications
  • One-Shot Rising and Falling Edge
  • Software in Rockwell Automation
  • S7-1200 Hardware Configuration
  • Factory IO and Siemens Tia Portal
Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address
You've successfully subscribed !

Continue Reading

Use of Comments in SCL Language
Understanding the Scan Cycle of SIEMENS PLC
Edge Detection in PLC Programming
How to Work With Simulator in S7-1200 and S7-1500 PLC?
How to Password Protect HMI in Siemens TIA Portal?
UPS Selection Factors for a Control System
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
Leave a Comment

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay Connected

128.3kFollowersLike
69.1kFollowersFollow
210kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

Automate Batch Mixing with Repeated Cycles in Omron PLC
Types of Failures in Industrial Automation Systems
DeMorgan’s Theorems using Ladder Diagram
Automatic Door Operation PLC Programming and Simulation
Siemens S7-300 CPU Suffix Explanation
Augmented Reality and Virtual Reality in Industrial Automation
Configuration of Siemens VFD Using TIA Portal Start drive
Safety Considerations in PLC System Design

Keep Learning

Code Simulation of Safety Circuit

Feedback Monitoring in Safety PLC

OpenPLC - PLC Training for Students - Free Tutorials & Courses

OpenPLC – PLC Training for Students – Free Tutorials & Courses

Understanding Braking Theory in VFD

Understanding Braking Theory in VFD

Example Program Logic in Allen Bradley PLC

PLC Programming Examples on Industrial Automation

Siemens Tia Portal PLC Training Course

Siemens Tia Portal PLC Training Course

Best Practices of PLC Wiring

Best Practices of PLC Wiring – Programmable Logic Controller

AI AO DI DO Questions

AI, AO, DI, DO Questions (PLC I/O Types)

Two-Conveyor PLC Control System

Basic Conveyor System for Product Handling in Omron PLC

Learn More

Measurement and Instrumentation Objective Questions

Measurements & Instrumentation Quiz – Set 2

parallel-resistors-circuit-example

Series and Parallel Resistors

PLC Battery

Everything You Need to Know About PLC Battery

AC Generator Operation

Losses in AC Generator

DP-Transmitter-with-two-seals

DP Transmitter with Two Seals applications

Valve Basics, Sizing, and Actuators Books

Valve Basics, Sizing, and Actuators Books

How to use Scale and Normalize Instructions in PLC

Scale and Normalize Instructions in PLC

Spectrometers Questions and Answers

Fluorescent Spectrometer Questions & Answers

Menu

  • About
  • Privacy Policy
  • Copyright

Quick Links

  • Learn PLC
  • Helping Hand
  • Part Time Job

YouTube Subscribe

Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Welcome Back!

Sign in to your account

Username or Email Address
Password

Lost your password?