achrn wrote:I think we need to know how the adapter is configured to say much.
If it's just a passive connection of a GPIO to the one-wire bus with a pull-up resistor, then it will probably be less good with long buses than if it's a dedicated driver chip (such as a DS2482-100). If it runs teh 1-wire bus at 5V or at 3.3V may affect reliability too.
If you don't already know what your hardware is, what are the markings on the chips are on the adapter, and how have you configured your Pi to talk to it?
Well, in my first post I stated what adapter I have, but anyway, here are more details:
General: http://www.abelectronics.co.uk/products ... and-1-Wire
http://www.abelectronics.co.uk/docs/sto ... -ComPi.pdf
And more about the 1-wire:
http://www.abelectronics.co.uk/docs/sto ... S2482S.pdf
And yes, my Pi talks OWFS quite well, I do see the first two sensors IF the long heavy cable is disconnected on either end. However, when I connect the long cable, all sensors disappear, but OWFS is still there. So I believe all is good with the Pi.
Your long cable is very heavy - I've only used cat5, cat6, 0.2mm2 conductors and similar. With those, driven by a dedicated driver, I've not had problems with 20m+ and 10 or more DS18B20s.
Yep, I know it is heavy, I originally planned using my old long parallel port cable, which has a lot of wires, but it was not long enough. Basically I chose the heavy cable as it was long enough. I thought it would have no relevance on which cable I used. I thought one point of the 1-wire was that it does not have much requirements for the cable type or thickness.
I do have some cat6, but probably not enough for this.
When you who understand more about this look at the Com Pi adapter and it's RJ12, to what pins would you have connected which pins of 18B20? I connected simply GND-GND, Data-Data and Vdd-+5V. Now that I look at the technical details of the Com Pi, maybe I should have used RT instead of standard Ground?
These are the Com Pi's RJ12 pins:
3 RT (1-Wire Return/Ground, ESD Protected)
4 OW (1-Wire Data, ESD Protected)
And now I have it so that 18B20's middle foot (2) is connected to OW-Data, right most (3) to 5V and left most (1) to Ground.
Well it seems to work with two 18B20's, so I thought it would be right..