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  • 0

IN1 and IN2 has 20V when nothing connected


Question

Posted

I want to connect a 0-10V temp sensor to the input IN2 on the Smart implant. The problem is that I have 20V on the green wire when nothing is connected. The same with IN1, yellow wire. I use a 24V power supply to power the smart implant.

5 answers to this question

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  • 0
Posted

I'm seeing similar but slightly different.

 

I'm seeing 0.8v on the lines as soon as they are powered from a 9v source.

 

In Home Assistant this matches what I'm seeing for sensor.smart_implant_voltage_4 state value

  • 0
Posted

Did you guys figure this out? I'm having the same problem. In my case, I want to use a pressure sensor that outputs 0-10Vdc. However, when bench testing, I discovered that even without the pressure sensor attached to  the SI IN1 yellow wire, I'm seeing 20Vdc across the yellow wire and ground. I'm using a 24Vdc 96W transformer. I'm using Hubitat (and the custom driver that is available on Hubitat) as the controller. Hubitat also shows 20Vdc, even when nothing is connected to the yellow wire. I have Input 1 defined on Hubitat as "Analog input without internal pull-up".

  • 1
Posted

I wouldn't be too concerned about the voltage on the input lines with nothing connected.  Try putting a 1M resistor between IN and GND and you should see almost 0V across the resister, proving that what you are seeing is just a floating voltage when nothing is connected.  It's safe to add a 0-10V sensor to these inputs.

  • 0
Posted

I saw your reply in the OP's other post on this issue. The problem I'm having is that it also reads 20Vdc when the pressure sensor's 0-10V output lead is connected to the SI's IN1 (yellow) lead. Also, applying pressure to the sensor's high pressure port doesn't change its output voltage (it stays at 20V) when it is connected to the SI. However, if I disconnect the sensor from the SI, the sensor's output lead does show 0-10V depending on the pressure put on the high pressure port.

 

In case I have it wired incorrectly, here is how I wired it up...

 

I used the diagram shown in the SI doc in topic "4.6: Connection with 3-wire 0-10V sensor" on page 4. The pressure sensor and the smart implant are powered by the same transformer (24Vdc 4A). I connected the transformer to the sensor's terminal 1 (common) and terminal 2 (24Vdc input). It is also connected to the SI blue wire (ground) and red wire (power). The SI IN1 (yellow) wire connects to the pressure sensor terminal 3 (Vdc output). I do not have the sensor common and SI ground connected with a wire because I assumed they are implicitly connected when they are using the same negative/ground/common from the transformer. The SI's parameters 20 and 21 are set to 4.

 

Here's a link to the one page doc for the pressure sensor. I'm using sensor model # SPD70-010...

 

Please login or register to see this link.

  • 0
Posted
On 9/19/2022 at 6:17 PM, JustinLacy said:

I saw your reply in the OP's other post on this issue. The problem I'm having is that it also reads 20Vdc when the pressure sensor's 0-10V output lead is connected to the SI's IN1 (yellow) lead. Also, applying pressure to the sensor's high pressure port doesn't change its output voltage (it stays at 20V) when it is connected to the SI. However, if I disconnect the sensor from the SI, the sensor's output lead does show 0-10V depending on the pressure put on the high pressure port.

 

In case I have it wired incorrectly, here is how I wired it up...

Are you sure to have set the output to Analog WITHOUT pull up? Otherwise this output is lifted to the 24V input.

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