DS18B20 Temp sensors stopped working

[cvachon79]

My temperature sensors (4 of them) stopped reporting readings after a lightning storm. To my knowledge, my house was not hit.

I purchased new DS18B20 sensors in hopes that my existing sensors were bad but my GEM will not recognize the new sensors (I have followed the instructions for fining new sensor codes - enroll one sensor at a time). When searching for the sensors the following is displayed:
00-00-00-00-00-00-00-06
00-00-00-00-00-00-00-86
00-00-00-00-00-00-00-46
00-00-00-00-00-00-00-C6
00-00-00-00-00-00-00-26
00-00-00-00-00-00-00-A6
00-00-00-00-00-00-00-66
00-00-00-00-00-00-00-E6

In my previous setup up I did not need a pullup resistor. I also only enrolled one new sensor.

I have tested the GND and 5 volt leads and confirmed the GEM is producing 5v. I've also updated the COM software to the latest version (ENG is also latest version). Still no luck. How can I trouble shoot this? I would think if this is a result of a Lightning strike or power surge - other functions of the GEM would not work.

Thanks for the help!

COM firmware ver: 4.22
ENG firmware ver: 1.49

[Teken]

The first thing I would try is unplug the GEM and completely remove power from the unit. This means unplug the PT and PSU transformers along with the battery coin cell within the unit. Wait about 30 seconds and plug the GEM's PSU & PT.

Once its up insert the coin cell and try again . . .

[ben]

Maxim has a post on making reliable one-wire networks here you can flip through: https://www.maximintegrated.com/en/app- ... mvp/id/148

The issue with 1-wire is that every environment can be different. You could try putting a strong pull-up resistor between 1-wire and 5V (4.7k ohm if you have it).

The first thing I would try is unplug the GEM and completely remove power from the unit. This means unplug the PT and PSU transformers along with the battery coin cell within the unit. Wait about 30 seconds and plug the GEM's PSU & PT.

Once its up insert the coin cell and try again . . .

If it's a newer unit, the battery has been replaced with a super capacitor. Removing power from the super capacitor is done by removing the header above the Ethernet jack on board.

You only want to remove this while powered on to make sure you don't cause any issues with memory when powered off. Then only put it back on when powered on.

[cvachon79]

No luck... I unplugged PT and PSU transformers along with the battery coin cell within the unit. I waited several minutes and then plugged the GEM's PSU & PT back in and then inserted the CR battery (my unit is from Sept 2014).

When the GEM booted back up and I selected the "Temp Degree" tab my old sensors codes appeared in the "Search, List all sensors codes" section. When I selected Search - it found nothing (I have one sensor connected). I have also tried a 2nd sensor to rule out a defective sensor.

I doubt I need a pull-up resistor as it worked fine 2 weeks ago...however I will order one and give it a try.

Any other thoughts on trouble shooting?

[Teken]

No luck... I unplugged PT and PSU transformers along with the battery coin cell within the unit. I waited several minutes and then plugged the GEM's PSU & PT back in and then inserted the CR battery (my unit is from Sept 2014).

When the GEM booted back up and I selected the "Temp Degree" tab my old sensors codes appeared in the "Search, List all sensors codes" section. When I selected Search - it found nothing (I have one sensor connected). I have also tried a 2nd sensor to rule out a defective sensor.

I doubt I need a pull-up resistor as it worked fine 2 weeks ago...however I will order one and give it a try.

Any other thoughts on trouble shooting?

Can you confirm you have only (1) brand new sensor connected to the GEM now? Its been awhile since I read the full users manual but recall there was three ways to detect or enter the 1 wire MAC code.

Review the manual and see what it says I'm not close to a computer so can't read the manual. If none of that works its probably best to engage Brultech directly to see if there are other next steps. The only thing that comes to mind is possibly resetting the GEM to a OEM state.

It would probably be a good time to take a back up of the settings first using the network tool. But would suggest you let Ben / Paul take a look and see if there is something else.

[ben]

No luck... I unplugged PT and PSU transformers along with the battery coin cell within the unit. I waited several minutes and then plugged the GEM's PSU & PT back in and then inserted the CR battery (my unit is from Sept 2014).

When the GEM booted back up and I selected the "Temp Degree" tab my old sensors codes appeared in the "Search, List all sensors codes" section. When I selected Search - it found nothing (I have one sensor connected). I have also tried a 2nd sensor to rule out a defective sensor.

I doubt I need a pull-up resistor as it worked fine 2 weeks ago...however I will order one and give it a try.

Any other thoughts on trouble shooting?

How far is the sensor extended?

Do you have a multimeter? If so, measure between the GND and V lines, you should get around 5V, between GND and DATA between 4-5V.

[cvachon79]

GND and V lines = 5V
GND and DATA = 1.3V

I switched out the wire and received the same readings (wire length less than 6 inches).

[ben]

GND and V lines = 5V
GND and DATA = 1.3V

I switched out the wire and received the same readings (wire length less than 6 inches).

Can you check the voltage between GND and Data with no sensor connected?

[cvachon79]

Sorry - those readings were with NO sensor connected. Tested w/ sensor connected and they are the same.

I also measured V line to DATA and that was 3.8V.

In summary:
GND and V lines = 5V
GND and DATA = 1.3V
V line and DATA = 3.8V

[ben]

Sorry - those readings were with NO sensor connected. Tested w/ sensor connected and they are the same.

I also measured V line to DATA and that was 3.8V.

In summary:
GND and V lines = 5V
GND and DATA = 1.3V
V line and DATA = 3.8V

Sounds like there's an issue with it pulling it up, can you try putting a pullup between DATA and 5V, then take a new reading?