Hi, I'm trying to develop a wireless I/O transparent bridge. This is for industrial applications. The idea goes after eliminating the use of cables where a machine is moving 24/7, so sensors mounted on a moving section of the machine can be read and written over a wireless connection. I've checked nrf24i01 and ESP32 as potential candidates, but I lack experience to assess the right path to follow. Also, I've read about LoRa point to point communications. For home appliances I guess that the NRFs are quite good but for industrial applications there's a great monster to defeat: EMI. This system must be "very" reliable, and eliminating EMI sensitiveness is a must. Of course there are other issues to overcome like connection stability, real time (speed) responsiveness, and reliability on the data obtained. One important thing to have in mind is that 1s and 0s are not changing at kilo or mega hertz frequencies, these are typical sensors like inductive or photoelectric, so talking about bytes or words has no sense whatsoever.
I would really appreciate any help from anybody in this topic,
thank you!
Wireless serial modules have been around for a long time. They replace UART serial transmission cables. The HC-12 is popular for use with Arduinos.
talking about bytes or words has no sense whatsoever.
It makes excellent sense and is essentially unavoidable, since almost all the available radio modules are packet oriented, with error detection.
For a very simple, short range, wireless 4-bit I/O repeater, you might consider something like these radio modules (which operate internally on a packet basis, hidden from the user):
Why? High-flex cable designed for this kind of application is a thing.
If cables will not work for you, how do you intend to power your devices? No one wants failures because the batteries are dead.
Well, Olflex Robot 900P is an extremely reliable cable for this, but wireless offers unlimited connection though, no more cable worries. It's about making a step forward, taking the advantage of technology that 25 years ago was so much difficult to develop and implement.
Well, I'm thinking on using a 18650 battery powered moving module, plus a wireless charging module, that is a transmitter and receiver. The robot is idling several hours a day, so the two coils will be facing each other during these downtime hours (home position), allowing the battery/s to charge. The sensors I'm using are hall type, like this one, which has a consumption of less than 1mA. Working time will never ever drain the batteries. The wireless data transmitting device is what keeps me awake, not knowing what would be most reliable approach. I need to overcome two main situations: EMI and instant and automatic wake up capability after power down.
Well, you have a solid point regarding error detection..But, you later mentioned the 4bit I/O repeater, which is basically what I need. There's a couple of insights: first, I want to develop something robust, reusable on other projects, expandable as well for being bidirectional. Second, I need to replace the button command by PLC ready I/Os. The nice feature is that communication does not need to be established first, it's permanently open and listening the 433 frequency signal, something that is obliged on my project, since a power loss on the stationary 24V side cannot need an external action to reconnect, it has to be immediate and automatic.
Not bidirectional, in its present configuration. The buttons can of course be replaced with logic inputs. The encoders and decoders are readily available PT2262/72 chips.
Well, if it's not bidirectional I cannot choose to go this way. Additionally, at the present time I need to solve this quickly, no time for PCBs or electronic engineering, though I save my intentions to analyze this further in the future. I've read the PT2262 datasheet, seems pretty convenient for a unidirectional application though, btw, just like a remote for the garage gate or something like that.
No, It's not. Your garage door opener has immediate feedback. That is you or the operator. If it fails, you know and can take action.
I think this is what you're looking for.
https://www.bannerengineering.com/us/en/products/part.87094.html
Likely to be more robust and suitable for your environment.
Have you considered that a 433Mhz system will have legal duty cycle limits in most places in the World, in that the repeater transmitter can only be transmitting\repeating typically 10% or maybe 1% of the time ?
Honestly, I haven't, you're correct. So I guess that 433 is out of question. So the search narrows down to nrf24i01 or ESP32 in the 2.4GHz band. What do you guys think?
This solution is out of scope, due to budgetary limits...
Is your time spent on this project FREE?
Well, using the 2.4Ghz band does allow for much higher duty cycle, 100% even.
But would nrf24i01 or ESP32 have enough range ?
No it's not.
Range is not being longer that 2m at any time.