Reading Data from analog input VM110

Hi! Can anyone tell me how can i read data from the analog gas sensor by using vm110 ? the gas sensor has variable resistance…Can i read the output voltage from the sensor and convert it to the data?

Could you give some more info about the gas sensor: type and manufacturer or link to the data sheet.

Of course! Here is the link: figaro.co.jp/en/pdf/2611ProductInfo0205.pdf

Connect he upper end of the load resistor RL to the analog input of the VM110 and the lower end to GND.
You have to use external 5V supply for the sensor.
Select proper value for the RL according to the specification. Better to use a variable resistor of 10k ohm in series with a 470 ohm fixed resistor.

[quote]A common power supply circuit can be
used for both VC and VH to fulfill the
sensor’s electrical requirements. The
value of the load resistor (RL) should be
chosen to optimize the alarm threshold
value, keeping power dissipation (PS)
of the semiconductor below a limit of
15mW.[/quote]

[quote=“VEL255”]Connect he upper end of the load resistor RL to the analog input of the VM110 and the lower end to GND.
You have to use external 5V supply for the sensor.
Select proper value for the RL according to the specification. Better to use a variable resistor of 10k ohm in series with a 470 ohm fixed resistor.

[quote]A common power supply circuit can be
used for both VC and VH to fulfill the
sensor’s electrical requirements. The
value of the load resistor (RL) should be
chosen to optimize the alarm threshold
value, keeping power dissipation (PS)
of the semiconductor below a limit of
15mW.[/quote][/quote]

Thanks! But i have another problem. When i read data by ReadAnalogChanel on first channel i always have 7(or 8) and on the second channel always 254…What’s the problem here?

Have you removed jumpers SK2 and SK3?
Adjust the trimmers RV1 (ATT1) and RV2 (ATT2) to max position.

Does the test mode when jumpers SK2 and SK3 are installed work OK?
If you in this mode adjust the trimmers RV1 (ATT1) and RV2 (ATT2) do you get values 0 to about 255 using ReadAnalogChanel ?

[quote=“VEL255”]Have you removed jumpers SK2 and SK3?
Adjust the trimmers RV1 (ATT1) and RV2 (ATT2) to max position.

Does the test mode when jumpers SK2 and SK3 are installed work OK?
If you in this mode adjust the trimmers RV1 (ATT1) and RV2 (ATT2) do you get values 0 to about 255 using ReadAnalogChanel ?[/quote]

If i remove jumpers SK2 & SK3 i read 0 from analog input with no sensor connected and there is no voltage between GND & A1 (or A2). If i install jumpers, i read 7(8) and 254 from the same analog channels, but i have +5v between GND & A1 (or A2). Is this correct?
So, what i should do? I suppose the next steps:
1 Remove jumper from SK2
2 Connect the sensor’s heater pins to SK2 pins
3 Connect one end of the load resistor to (-) pin of sensor and to GND
4 Connect the other end of the load resistor to A1
5 Connect (+) pin of sensor to +5V voltage from SK2

Am i right?

It is OK that you get +5V from A1 and A2 if the jumpers SK2 and SK3 are placed. Also OK that you get values about 0 to about 255 if you adjust the trimmers ATT1 (RV1) or ATT2 (RV2).

Your description of the connection of the gas sensor is not OK.

Please look the application circuit diagram for the gas sensor how the load resistor should be connected in series of the sensor. Do NOT connect the (-) pole of the sensor directly to GND!

Also the heater needs to be connected between +5V and GND.

Hopefully the current consumption is not too high for the USB. The total current (VM110 + the gas sensor) should be less than 100 mA otherwise the USB output of your PC will be blocked.

I connect the gas sensor and it’s works just great! Thanks a lot for your help!