Question

Hi, 
I "NEED" to monitor a battery voltage which might in some rare condition exceed 24Vdc.
To avoid damaging the analog input of the RUT955 I wish to use an external potential divider circuit like this:

I presume that the ADC input in the RUT955 has an impedance (which would be in parallel with R2) and so cannot select the divider values without knowing this.

Please can you give the "resistance" of the Analog input, so that I can calculate the potential divider resistor values?

Others might find it useful if the wiki were updated with this information too.

Many thanks
Alex

Answer 1

Hello,

In order to answer your question I am going to need router's hardware revision number. You can find it in the Status -> Device page.

Comments

Thanks, it's offline at the moment and 30km away, but I did record this information before sending it to site :o)
Teltonika RUT955 H7V3C0 Batch No 030 HW Rev 1106

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Hello,

The series sum of the internal divider resistances is 131K. If your maximum signal voltage is lets say 30V, you can use 8.66K series resistor and 47K parallel resistor to get 24V at router's input.

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Thanks folks.

That's great!

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Can You tell me the internal impedance for DIN1 (latest hardware revision)?

Answer 2

I have the same request - max Voltage 30V

My RUT955 is T033C0 -  Batch 051

Many thank, Peter

Comments

Hi Peter,
I used a 2k multiturn potentiometer and adjusted on-site to yield a 1.5:1 multiplier.
Bon chance
Alex

Answer 3

I made a measurement for DIN 1, You find it here: https://community.teltonika-networks.com/26636/input-impedance-rut955.