NRCHKB

OMRON PLC

Updated July 19, 2022 by luwol03 and Shaquu

What Is a Programmable Controller?

A programmable controller (PLC) has a microprocessor and controls devices through custom user programs. A PLC receives signals from input devices and makes decisions based on custom programs to control output devices.

Read more about OMRON PLC

Why use a Programmable Controller with Node-RED?

A PLC is by definition Automated, which means that the role of Node-RED is to be a Human Machine Interface (HMI). This term defines any device allowing a user to interact with a device in an industrial environment.

The role of Node-RED is going to be a Gateway between PLC and Home.app because an advantage of using a PLC is that its programming is not complicated. Indeed, the Ladder Diagram (LD) language is widely used and above all very easy to understand, unlike DIY solutions with their multiple language and communication protocol for example.
Another advantage is that it is cheaper than the KNX System.

Using in Node-RED

For that you must do the following points:

Install

Install node-red-contrib-omron-fins and node-red-contrib-buffer-parser using Manage Palette

Configure

FINS Read and FINS Write nodes

To put the Read Addresses you have two nodes:

  • FINS Read in which you put a starting address and the number of addresses you want to read after it.
  • FINS Read Multiple in which you put addresses you want.

And to put the Write Address you have FINS Write node.

For the bridge configuration, please visit this instruction

Warning! We can only write to one address at a time!

Buffer-Parser node

This node allows for our use to convert an Int16 to 16bits. Indeed the read nodes return an Int16 list.

Buffer Parser Example

We can exploit the response of the node with:

msg.payload = {
    "CIO100": msg.READ_PLC.CIO100[0].bits,
    "D100": msg.READ_PLC.D100
};
return msg;

To convert 16bits back to Int16 use this in a Function node:

let READ = msg.READ_PLC.CIO10[0].bits;

READ = READ.reverse().toString().replace(/\,/g,'');

msg.WRITE = parseInt(READ, 2).toString(10);

return msg;

Example flows

Here is a list of examples that you can go to visit:

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