Technical > Wiring & Sensors

Nernst target help, please..

(1/1)

Bat:
Hi,
I'm trying to do this ....

Pump PID nernst target

Once you are satisfied that wbo2_pump_pw_zero is as close to 0v as it can be (done this got 0.017v), you should verify the pump and nernst control voltages. You'll need two 100 Ohm resistors. Power down the board then

    * insert one 100 ohm resistor between wbo2_pin1 and wbo2_pin6
    * and the other 100 ohm resistor between wbo2_pin1 and wbo2_pin5.
    * Power up the board, and switch to LCD page 2 using the command Manmlp02 and display the page with the command mll
    * Enable the WBO2 heater with mde02, and wait for the O2% to be displayed by refreshing the display with mll. (can only get ??.? here after 5 minutes. What does switching on the heater achieve here, nothings connected to it? )

Just to verify, check that the voltage between ground and wbo2_pin5 (nernst-) (Confused here, nernst signal is on pin 1 and WBO2 pump- is on pin 5  ???)reads appr 4V. 3.9V .. 4.1V is perfect. Note that this cannot be change in configuration or firmware, it's controlled by hardware. If less than 3.8V or above 4.2V, there is good chance the wiring is bad, check it.

All help gratefully received :)
Cheers,
Gavin :)

rob@vems.co.uk:
The resistors complete the heater circuit, so the idea is that you switch the heater on, the controller goes through the heat cycle and allows you to tune the system.

If you're still getting ?.?? then theres a problem somewhere, use mlp07 to see what the heater values are.

Rob

Bat:
Hi,
Thanks for the reply Rob.
Are the pin numbers correct for connecting the resistors, and testing the voltage, as (nernst -) is neither nernst signal or (WBO2 pump -)
Cheers,
Gavin :)

Bat:
Hi,
Sorted :)
Don't know why I bothered worrying about calibrating it, when I plugged the sensor in it read 20.8!
I think the Hungry people(lol) must have done it for me?
Cheers,
Gavin :)

rob@vems.co.uk:
I think you struck lucky with the sensor there then!
I'd calibrate the sensor so that its giving 20.9 to 21.0 consistently.
What sort of nernst and pump_pw values did you get in the end, they tend to be in a small range of values.

Rob

Navigation

[0] Message Index