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Sensor Data Over Long wires

Posted: Mon Jul 02, 2018 2:11 pm
by shreyasmishra12345
I am trying to do a project where I have three different ultrasonic sensors fitted at three different places of my house and I have one Raspberry Pi. I cannot use the normal jumper wire since they are very small in length. Can I use normal line wires to connect those sensors to my Raspberry Pi? If not which type of wires should I use?

Re: Sensor Data Over Long wires

Posted: Mon Jul 02, 2018 2:49 pm
by mahjongg
Yes, you could use phone line wire, (for example) but using any device over long wires can bring problems.
One of the first things we need to know whether you are likely to suffer them is which exact (ultrasound) sensors you are using, and what interface method do they use. Using just thicker wires is NOT always going to help.

Re: Sensor Data Over Long wires

Posted: Mon Jul 02, 2018 3:33 pm
by shreyasmishra12345
Actually the longest distance between one sensor to the Pi 3 is about 15m. Will there be any problem within that distance? Also is there any way of transferring sensor data from sensor to Raspberry Pi over WiFi without physically connecting them?

Re: Sensor Data Over Long wires

Posted: Mon Jul 02, 2018 10:14 pm
by Z80 Refugee
You would be better off with three RPis (one at each location, running each sensor) which then communicate with each other via Ethernet or Wi-Fi.

Re: Sensor Data Over Long wires

Posted: Tue Jul 03, 2018 3:31 am
by shreyasmishra12345
Yes, that will be good, but I gotta work with what I have. So can data be transferred over that distance(10-15 metres) without loss?

Re: Sensor Data Over Long wires

Posted: Tue Jul 03, 2018 8:39 am
by Z80 Refugee
If you are working with digital data output from a self-contained ultrasonic module, yes (with due consideration to making sure the data actually gets from A to B). If you are trying to operate just the transducers with the actual transmit and receive circuits elsewhere - I would say no (or at least not without spending so much on suitable cables as to be not worth it).

Re: Sensor Data Over Long wires

Posted: Tue Jul 03, 2018 8:49 am
by Gavinmc42
Use RS485 chips to convert it to lvds, then 15m is nothing.

Re: Sensor Data Over Long wires

Posted: Tue Jul 03, 2018 9:02 am
by B.Goode
I am trying to do a project where I have three different ultrasonic sensors fitted at three different places of my house and I have one Raspberry Pi. I cannot use the normal jumper wire since they are very small in length. Can I use normal line wires to connect those sensors to my Raspberry Pi? If not which type of wires should I use?
Actually the longest distance between one sensor to the Pi 3 is about 15m. Will there be any problem within that distance? Also is there any way of transferring sensor data from sensor to Raspberry Pi over WiFi without physically connecting them?
So can data be transferred over that distance(10-15 metres) without loss?

Two comments:

First - rather than relying on anecdote and opinion in an online forum, read the datasheet or specifications of the sensors you are trying to connect to determine the design limits of the signals they send and receive.

Second - maybe an alternative - put an RPi and a sensor on your 'workbench', connect them with 15 metres of 'normal line wire' and see it it works.



Puzzled by this:
is there any way of transferring sensor data from sensor to Raspberry Pi over WiFi without physically connecting them?
Using WiFi would not involve physically connecting them. But if the sensors already have WiFi why not just use it?

Re: Sensor Data Over Long wires

Posted: Tue Jul 03, 2018 9:38 am
by btidey
In general I avoid long wires connecting sensors for a number of reasons.

1) Potential technical difficulties making them work. Can be overcome in some situations but you also have to supply power to the sensors adding to the difficulty.

2) The aesthetics of having wires trailing around. Can be overcome if suitable routing is available.

3) Lack of portability in positioning the sensors.

For modern usage wifi is the preferred medium for remote sensors. As someone said this could be achieved by Pi (or Pi0w) but this is overkill for most sensor applications. ESP8266 modules provide an effective and very low cost option for remotely connecting by wifi sensors back to a central Pi server. They can be got in a breadboard friendly nodeMCU format or as raw modules like ESP-12F for even lower cost if one has some reasonable hardware integration skills. As they are arduino compatible there is an extensive range of libraries covering most sensor types including ultrasonics. The remote esp connected sensor can either have just a local power connection or in some cases can be battery powered particularly if deep sleep methods are used.