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On the wiki page https://wiki.teltonika-networks.com/view/RUT955_Inputs_in_Security_Applications it says "Note: you can only connect passive sensors to RUT955' digital input." But on the page https://wiki.teltonika-networks.com/view/RUT955_Input/Output it gives me values for what is considered high and low:

"Digital input (DIN1): Logic low 0 - 1.2 V; Logic high 1.8 - 3 V"

So, what is true? To me, a "passive sensor" ist like the example: a switch shortening the Inputs or leaving them open. But then, the voltage statement doesn't make sense.

So, can I put a voltage potential in there or not?

What I want to do is, evaluate the output of a microprocessor (low: 0 v, high: 3.3 V) with the RUT955. Can I just connect my output into DIN1 on the Router?

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One more question arises: What is the input impedance of DIN1?

2 Answers

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Hello, 

Here is a sample scenario for the Digital input (Pin1) and GND (Pin6) of RUT955 with the use of push button. 



When the button is not pressed the state will be open and when its pressed it will be shorted. 



Hope it helps

Regards,
Jerome

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It's the same scenario as in the first link i posted. So, how is your answer supposed to help?

Please read the question carefully. It's about a (presumed) contradiction in the wiki pages. And about connecting a microcontroller to the router, not a button.
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Hello,

If you are connecting a microcontroller its best to show the whole electrical diagram an may i know what are you trying to achieve??

So, can I put a voltage potential in there or not?

-> Digital input (DIN1): Logic low 0 - 1.2 V;  Logic high 1.8 - 3 V, So if the voltage is 0-1.2V the status will be open and when the voltage input is 1.8-3V it will be high.

What I want to do is, evaluate the output of a microprocessor (low: 0 v, high: 3.3 V) with the RUT955. Can I just connect my output into DIN1 on the Router?

-> It is best to connect GND port also on the output of your Microcontroller. So the ouput ground (controller)  will be having a connected to the  ground of the microcontroller. Just keep in mind that it is best not to exceed 3V in the Digital input.

Regards,
Jerome
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So, do You see the contradiction on the mentioned wiki pages? It's a different thing, whether I connect the pins with a button (as described in You first answer too), or whether I put a voltage potential in it (as described in Your second answer).

An electricial diagram should not be needed to answer the question, if it is ok to put (active) voltage in there and how the contradiction can be solved, either by explanation or by correction.

It is best to connect GND port also on the output of your Microcontroller.

Of course I'll do, otherwise I would'n have put in the voltage potential I spoke about. There's no voltage with only one pole!

So the ouput ground (controller)  will be having a connected to the  ground of the microcontroller.

To understand You right: Do You mean the router by the word "controller" and the DIN1 by the word "output"? DIN1 is an input!

Or Do You mean different grounds on my microcontroller's side? My microcontroller is an ATTiny85, it doesn't have a seperate output ground. I'm not even aware that microcontrollers exist, that do so.

The microcontroller's output is a push-pull output, not open collector. That's why it really gives out a voltage on "high" and can even supply a ponderable current.

What ist the maximum allowed voltage on DIN1? The Wiki only says, what is considered high, not the absolut maximum rating. I had hope, that 3.3 V are just ok.

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Hello, 

So your main concern is if you can put active voltage input on the DIN1 Input of the RUT955. I am right? 
Digital Input (PIN 1) is designed for passive sensors / inputs. 

See I have connected D1 to Analog input. Here is the results it is giving D1 is giving out a voltage of 2.58V 

So you don't need to supply any voltage input to D1 as it is mentioned before it is designed for passive inputs/sensors.

I hope it clarified now. 

Regards,
Jerome

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You still don't understand the question. As I wrote (several times!), the microprocessor gives out a voltage when "high". And this I want to evaluate on DIN1.

So, what sense does it make to say "you don't need to supply any voltage"? The question was not, If I _need_ to supply, the question was, is it _allowed_.

And further on, what's the maximum allowed input voltage?
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Hello,

As what is found on wiki the maximum voltage is 3V.

Regards,
Jerome
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Ok, thank You. But as said, this ist not indicated as the maximum allowed. Has someone else  further information? Can someone tell the type of microchip or a schematic of this input device?
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Hello, 

For the circuit design and schematic diagram of the Input/Output design we cannot provide it.

But for the where i got the information about the 3V MAX rating for DIN1 you can refer to this link: 
Teltonika RUT955 User manual (solwise.co.uk)

Regards,
Jerome

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There I found it, on page 142. Thank You. I think, that belongs into the wiki, since this is the source of information I get routed to when clicking on "user manual" on the product page! It's sad, that a third party has better documentation available... Teltonika, please fix that!

Also, this manual I wasn't aware of, shows, that any push-pull outputs of external devices should not be connected to DIN1. They can go into DIN2, but that has the wrong voltage level. My 3.3V there are still considered "low".

So, ok, now I know what to do: make my push-pull-output into an open collector by adding a transistor.
0 votes
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I measured the input impedance, You find it here: https://community.teltonika-networks.com/26636/input-impedance-rut955