DS18B20 distance

[shantanu@india]

Hi,
I am using these:
https://robu.in/product/ds18b20-water-proof-temperature-probe-black-1m-2/?gclid=CjwKCAiAvaGRBhBlEiwAiY-yMIDE2oQE6RpXdALElalVoHshTgPVCmIUtotAPvFe97hmik33DGBbDBoCO5EQAvD_BwE

Can I extend the wire using unscreened cable upto 25 meters?

[top204]

Unless a user has already placed a one-wire device on a long lead, there is only one way to find out. :-)

There will be voltage drop and noise on the line, but they are very slow devices, so the noise should not effect them as much, unless it is extreme AC noise from motors etc...

When testing it, and it does give an initial reading, power up some motors and bring them close to the wires and see if you still get readings. Also, twist the wires to give an element of noise protection.

[evoortman]

Hi,

This depends on the capacitance of the cable and the value of the pullup resistor.
The longer the cable, the lower the resistance should be.

[shantanu@india]

Thanks Les, Evoortman.
Yes I need to try out first.
Just been reading a Maxim application note where they have mentioned 'wire weight' which apparently varies with topology, no. of devices, cable capacitance etc. It seems one wire technology can be used even upto 200/250 meters with suitable protection

[shantanu@india]

Evoortman your suggestion worked... Thanks!!
I was using the internal pullup of 4.7K which was not sufficient. I had to use 1K for a 10 meter long cable.

[chris_cb_uk]

These devices are good, but so painfully slow to communicate with!

[Yasin]

In fact, there is almost no chance of errors in reading. If the data read does not pass the CRC verification, you will not be considered.

[towlerg]

These devices are good, but so painfully slow to communicate with!

In a way that one of the beauty's of this device. Noise immune and only a few wires (one less if you use parasitic). If you need updates quicker than one every second or two, look at some other device.

[shantanu@india]

In a way that one of the beauty's of this device. Noise immune and only a few wires (one less if you use parasitic). If you need updates quicker than one every second or two, look at some other device.

You're right.
I have rarely come across any process control where the temperature changes very fast. In fact temperature is a sluggish parameter.