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I have many FMB120 devices  with a single dallas 18B20 temperature connected. When the device is in normal mode, the AVL data is transmitted regulary, and I can see the temperature value.

When the device go in sleep mode (ON LINE SLEEP), the device is configured to send a record every Hour, but in this case, the AVL event is missing and there is not temperature value.

I Have set in FMB configurator:

Dallas Temperature 1:

  • Priority: High
  • Low level: 0
  • High level: 0
  • Event only: no
  • Operand: Monitoring
  • Avg cons: 0

If can help, I have seen that when FMB120 is in normal mode, the voltage of 1-wire power is 5V. When device go in sleep mode (also when it wake up for hourly transmission) the voltage is 1.2V, that is non sufficient for to power up the 18B20 sensor.

My question is: Is normal that in sleep mode the device doesn't record any temperature value ? 

If I use it for to monitoring a remote place (such a truck with frigo cell, for example) I cannot use the sleep mode ?

Thank you.

1 Answer

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Thank you for your question.

Yes. It is normal.

In Deep Sleep and Online Deep Sleep  1 wire is shut down.

Best regards

Hello, thank you. 

Yes, I can  understand that, when the device is in sleep mode, the 1 wire could be off, but I don't understand why, after the device auto wake up from sleep mode for to transmit data, the 1 wire remain off and the temperature is not read.

I have set that device, when in stop, go to sleep mode after 10 minutes and will wake up (and transmit eventual records), every 3600  secs.

My question now is: It's normal that, when device automatically wake up from sleep mode (that you have set in "data acquisition" settings -> "on stop mode") , it doesn't read the 1-wire ?

Best regards.


The device wakes up ( not exit) from sleep mode - Deep Sleep and Online Deep Sleep to send data as configured but does not come out of sleep mode. So it is normal that it will not collect and send 1- wire data for ON STOP mode.

It will be able to do this after exiting sleep mode.

FMB exits deep sleep mode if ONE of following conditions is true:

Movement by accelerometer or configured movement source is detected;

Ignition (configured ignition source) is turned on

Best regards