Question

I tested dallas sensors with fmb641 device, and all worked fine, so I installed sensors to trailer with fmc640. After that I cannot read sensors. Device doesn't detect sensors. What should I do? Add pullup resistor to data line or what to check. Wiring seems to be ok.

Answer 1

Hello.

We would like to analyze your case, therefore please open ticket in VIP Helpdesk and provide all needed information: device IMEI, firmware version, configuration file. If you don't have VIP Helpdesk login. please contact with your Sales Manager. If you don't have any contacts with our Sale managers, please contact with them on our official website https://teltonika-gps.com/ and click on the "Contact Us" button. When you will click, please fill the form and submit it. Note: as a topic, please choose "Vehicle telematics".
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Comments

Hi, First I will go on site with some oscilloscope for check what I will find on 1-wire data line, then I will back with results.

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The solution is to use proper cable with low capacitance, and add additional pullup resistor betwen onewire VCC and onewire data line, I added about 3.8k and I'm able to connect sensors at 15m and at 30m on 30m length cable.
I hope it will run on site too.

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Unfortunatelly 1-wire starts to drop data during last week.
Today I checked cables and I did not find nothing interested.
I don't have any ideas why it is not working.