OneWire Temp Sensor Cable Length


#1

Hi,

for some reason the cable length of the temp sensors from the BrewPi shop are a bit too short for my setup.

If I increase the length with an RJ12 coupler and an additional RJ12 cable, do I get into trouble because of the cable length?
Are there any latency issues because of the longer cable, means that the temp reading from the sensors can take longer?

Thank you,
Thomas


#2

I have several of my 1-wire sensors spliced to about a meter of RJ11 cable, with no noticeable impact. There’s a wealth of info, perhaps more than anyone would care to read, on 1-wire here: https://www.maximintegrated.com/en/app-notes/index.mvp/id/148.


#3

The electrons themselves move much faster than the baud rate of the interface so any reasonable length shouldn’t be perceivable. The bigger risk would be voltage drop due to the small wire, but I actually have the control panel for my fermentation in a different room from the fermenters, so I’m running about 20’ between the two and have seen no issues.


#4

I recommend using cat5/cat6 ethernet cable and crimping some RJ11/RJ12 connectors on it yourself.
Store bought telephone cables are often very thin.
Several customers have reported solving all their problems by switching to ethernet cable.


#5

Just to understand it correctly. You suggest to connect from the brewpi with a cat 5 cable to the sensor with the original cable.

Should I shorten the original cable or leave it as it is?


#6

Sorry, I was confusing your topic with someone else, who had a 5m cable.
I would buy an RJ11 extension cable or RJ11 splitter.

You don’t need cat5 if it is just a short extension.


#7

No problem.

Thank you for this information. I will be around the 5m to 6m, so will test with a RJ11 extension and see if I face issues.


#8

I built my own brewery control system a few years ago using 1-wire sensors connected to a Barix Barionet 50. After reading all the lit, I decided to convert the sensors to “2-wire” mode, with a separate +5V line in addition to ground and data. I also inserted a 150Ω resistor in the data line near each sensor. With these changes, they’ve been very reliable. Also, it’s apparently fine to mix 1-wire and 2-wire sensors on the same network.