Need advice about remote message transfer

Dear Superiors,

I have and issue to give a solution.
I have two stations which are located 100m away from each other and i want to transfer strings from one statins to another. Master station is the always sending msgs to slave station. Slave station i only need to receive the string msgs and display in display board.

Since my master station has the PC what i tried first is made python tkinter gui and give master facility to enter his desired string msg and then by python i sent the string to arduino board and then transfer that master arduino data to slave arduino. Then i tried to display that slave arduino data on slave station P10 LED board. The process was quite hard with a lot of wiring and i don't think this is a reliable system since i want to run this system 24*7 hours per week.

What i want to ask from you is is there any opportunity that i can use two R-pies at master and slave stations and display that on PC monitor by using node red. Up To now i am thinking connecting those two R-pies via ethernet cables.

I am still at planning stage of this Use of R-pie for this project. Before i purchase hardwear i want to know that above mention is good or not? Is there any other reliable good method to do this task? All i want is transfer STRINGS from master to slave and display at slave station. Master station also need to display what he has sent to salve.

Provided you have some sort of working ethernet/wifi connection between the two devices then absolutely node red will do the job. Run node-red on the two devices and run an MQTT broker (mosquitto probably) on the PC and use MQTT to do the communications. That is extremely easy to do in node-red.
Node red has built in MQTT nodes for communicating with the broker. Here is a good introduction to MQTT:
https://www.hivemq.com/mqtt-essentials/

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If you wanted to keep the cost down, then as @Colin suggested you could run the MQTT broker on your PC.
There is also a desktop version of Node-RED that runs on a PC and a Mac.
It might not be the latest version of NR but it would do exactly what you wanted.
Then all you would need to do is purchase an inexpensive slave, for example a Wemos D1 Mini, which would allow you to "transfer strings", via MQTT, to the master - your PC.

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Thank you :slight_smile:

Great.:slight_smile: as you said i can install node red on master station PC or r-pie and connect both via cat6 cable to slave station Wemos D1 mini board and then use P10 LED panel to show that string right?

That is a good suggestion, if it can drive the display. That device has built in wifi so if your wifi will reach then that would do fine. I don't know whether it will do wired ethernet if that is necessary. A Pi zero would be another alternative.

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my master and slave stations are not have wifi . So i think i have to use ethernet wiring. Well now i have to learn how to make Wemos D1 Mini takes MQTT data :stuck_out_tongue:

Couple of notes.

(1) There are two versions of the Pi-Zero.
Pi-Zero with no Wifi, and Pi-Zero-W with WiFi.
Neither of them have an ethernet port, so a Pi hat like this world be needed to give it ethernet capability...

(2) Wemos D1 Mini has no ethernet capability, only WiFi.

(3) Could you change your master and slave stations to have WiFi capability ??

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Oops - sorry, I missed the bit about the P10 board.
I'll check if there are drivers for it (on the Wemos).

Do you actually need to use a P10 board, could an OLED panel work for you??

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Yeah i can purchase OLED panel if its working. Actually i am trying to build a machine size display. From supervisor room to machine operator station display. What i want to send is current product size and next product that the operators need to know. Then they can see the display and get ready for there work.Tomorrow i will arrange a wifi router at supervisor room and check whether it is discoverable to 100m away from there.
If yes we can connect ,ster pc or r -pie to that router and send string via wifi to slave station wemos D1 mini and display via OLED panel right?

i want big size screen ,at least 6 inch * 12 inch with scrolling string massage

For this purpose maybe an Arduino Uno with an Ethernet shield and a 2 or 4 line LCD screen would be the most reliable solution for the slave side. A display you could talk to using the standard library https://www.arduino.cc/en/Tutorial/LiquidCrystalDisplay

These displays are easy to read and mount to some enclosure for tidyness. The Ethernet shield equipped Arduino could then subscribe to a MQTT topic to listen for the messages.

Edit: I missed the display requirement. That big displays might require a Raspberry Pi to drive them. So maybe just one of those small monitors used as a standard HDMI display. A Raspberry Pi 3 would be sufficient to run a simple Node-RED dashboard on the slavs side to display the messages fullscreen.

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I want to display like this.

See my edited message above.

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Ah a LED matrix. Are you sure a regular display wouldn't be easier to read?

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cool. now i have the idea. to do this i will need 2 nos of r-pie 3 and 2 monitors one at master station and another one at slave. i will connect these two stations via ethernet and run NR on both pies. Then a nice dashboards are the rest i need to make right? :slight_smile:

Yes if you don't need a LED matrix like in the video that would likely be the simplest to setup. Driving a LED matrix from the Raspberry slave would of course also be possible but I don't know about the availability of ready made libraries. It would likely require some Python coding at least.

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so far i have did there is made python program ,made tkinter gui and sent msgs to arduino via serial communication and display that in that p10 board.
While doing so i faced few problems. when the string number of characters are getting high the msg is not fully showing in the display. Also i think i cant send 100m distance via serial communication. I will order 2 nos of R-Pie 3 and try this in a new way now. Thank you!!!

Good luck! With a standard PC display (or a flat screen TV for that matter) it should be straightforward. No messing with interfacing with specialised displays.

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I will have to dip-out on this as I do not have any experience of process control.
There are other people on the forum who do, so they may jump in.

Two things...

(1) You might want to think about using RPi-4B rather than RPi-3B. Here in the UK they are about the same price. However, the RPi-4B offers 1Gb ethernet. Although an "overkill" for your application, it might be worth considering. Even just using a RPi-4B for your master would be sensible.

(2) It would be useful if you published a specification for your application as it would help others suggest options/solutions for you. For example, is what you are doing a "demonstrator" or the "final solution" ??
I get the impression that if this works for you, you will probably want to replicate it for the workstations of other operators.

Good luck.

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Thank you alot for your feedbacks. Okey i will compare the prices of R-pie 3 and R-pie 4 in sri lanka. This is to make the peoples life easy using the new technology. :slight_smile: Again thank you very much for your help. For me i have to learn from start how to work with r-pie since i have no past experiences. :stuck_out_tongue: This issue was raised to find a final solution.