Advice sought regarding mesh networking devices

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efftek
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Advice sought regarding mesh networking devices

Post by efftek » Thu Jan 12, 2017 6:47 pm

Hi, I'm developing a system for monitoring machines. It needs to employ a self healing mesh network.

The system will have an STM32F103 on a board with a TFT screen and sensor inputs and also a Bluetooth module for connecting to smartphone for setting up etc. and I want to add a networking method onto the card.

Basically, I want a 'Master' unit which coordinates communication and sends data to a PC or to the cloud. The Master will maintain a list of 'Nodes' which is on its network and on a regular basis will request data from them.

So, lets say that the factory site is Acme and they have 3 machines, A Wabbit blower, a Woad wunner and a Fudd stirrer. The nodes are pre-programmed with which machine it is monitoring and when they are first powered up, they read the setup info from their EEPROM and they try to connect to a network eg

Node1 "Hello Master"
Master "Hello, Who are you"
Node1 "Wabbit blower"
Master "OK Wabbit blower you are registered"

Then the Master adds node 1 to its list and every so often sends out a message

Master "Hello Wabbit blower"
Node1 "Hello Master"
Master "Are you OK"
Node1 "Yes"
Master "OK Wabbit blower"
Master "Hello Woad wunner" ......
Master "Hello Fudd stirrer" ......

Then the Master updates the PC or Cloud and waits until pre-set time before asking again. In the meantime, let's say Wabbit blower has a problem

Node1 "Wabbit blower problem"
Master "OK Wabbit blower what is problem"
Node1 "Wabbit blower overheating"
Master " overheating logged OK"

Then the master updates the PC or cloud and waits until pre-set time to fond out if still overheating or OK.

Now, lets say node1 goes off line, the Master sends out message

Master "hello Wabbit blower" waits X seconds
Master "hello Wabbit blower" waits X seconds
Master "hello Wabbit blower"

deletes Wabbit blower from list. Updates PC/cloud "Wabbit blower missing"

When Wabbit blower comes back on line, we have a repeat of the situation where the node first powered up. The same goes for the other 2 machines.

There can also be a node who isn't monitoring a machine, its job is defined in EEPROM as repeater and is just there to extend the network where elements are too far away or obstructed by buildings, girders etc.

OK, so that explains what I want to do. The question is what technology should I use, XBee , Nrf or ESP. Which has the best and easiest libraries to use, which would be easiest for me as a 'network numpty' to write code for?

Thanking you in advance for your suggestions.

Steve.

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RogerClark
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Re: Advice sought regarding mesh networking devices

Post by RogerClark » Thu Jan 12, 2017 9:41 pm

You have not said what range you require. This will make a big difference in your choice of RF hardware.

Also does the link need to be encrypted ?

Your basic description glosses over the mesh part of the system e.g. where master cant communicate directly with specific nodes, and there data is relayed via other nodes.

I supsect when you list all available RF devices and rule out ones for which there isnt already a stable mesh networking library, and which have sufficient range.

The choice will almost be made for you, as there will not be many that fit the criteria

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efftek
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Re: Advice sought regarding mesh networking devices

Post by efftek » Thu Jan 12, 2017 10:11 pm

Hi Roger, as you may have guessed, I don't know anything about networks so these questions were not obvious to me. I don't see any need for encryption so that's not imperative to me. Most manufacturing sites have separate buildings, all have lots of metalwork both of which attenuate the signal so higher power would be preferable. But, this problem could be got round using the repeater's I mentioned to extend range. I would say that a range of 30 or so meters through a brick wall or two should suffice.

I think my priority would be a stable, easy to use library. Cost is less important than reliability. Is there a comparison of available devices, pros and cons, and discussion of libraries etc somewhere in a wiki?

Steve.

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RogerClark
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Re: Advice sought regarding mesh networking devices

Post by RogerClark » Thu Jan 12, 2017 11:08 pm

Steve

Sounds like you need some serious high end system.

You probably need to post to the various specialised forums, for the manufacturers of networking systems, or possibly a dedicated networking section on sites like the EEVBlog forum, or even the Arduino.cc forum's networking section (However I suspect what you are asking for is above the technical level of what normal Arduino.cc users would require or have knowledge of)

Ollie
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Re: Advice sought regarding mesh networking devices

Post by Ollie » Fri Jan 13, 2017 5:09 pm

Steve,

I do share very much the comments by Roger. I was following very closely the development of Honeywell One Wireless mesh and can confirm that it was a quite large undertaking over 10 years ago.

Now we have new technology available and it can be done with a lower effort. I am planning to do it and was asking some comments in this forum

http://www.stm32duino.com/viewtopic.php ... 71&p=21816

There were no replies for that request implying that it is not a generic interest among STM32duino readers.

Shinji
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Re: Advice sought regarding mesh networking devices

Post by Shinji » Sat Jan 14, 2017 11:25 am

Take a look at https://lowpowerlab.com/guide/moteino/

They use RFM69 transceivers and have slow (< 19200) connections over more than 30 meters.

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