Logging on C125 - need some insight please

[greenamex2]

Mine was right hand bends. Bit of a problem round most UK circuits!

[David Ferguson]

Here is sample boost controller - I am guessing that to find the frequency of my factory boost controller I will have to do some digging around but amusing I can find information similar to this: http://aemelectronics.com/files/instructions/30-2400%20Boost%20Control%20Solenoid%20Kit.pdf

These solenoids have two wires (pos and ground) should be tapping the positive wire and connecting that to the respective pin on the dash and disregards the ground wire? the dash (C125) is grounded to the battery just like every other part of the car.

There are several things you might do. First, configure the DIG/SPD input as a frequency input and monitor/display/log the frequency of the signal. After you know that, then you might want to change it to measure the period of the pulses, and now knowing the frequency you can convert that into a duty cycle value (which is probably the most useful for diagnostics).

As for wiring -- your boost controller is only going to control one of the wires -- the other will always be power or ground (and the control consists of grounding or powering the other side respectively). Connect your DIG/SPD input to the side that changes. You can certainly connect to one side and see what happens, then switch if you guessed wrong. I would say it's most typical to have one side powered all the time, the the controller grounds the other signal to control the solenoid.

[FoxSTI]

I wouldn't want to connect the "powered" wire to a digital input... those inputs are 0-5V and the solenoid run on 12v.
I am guessing that the duty cycle for them is done applying 12V at the respective frequency. someone told me that the factory solenoid runs at 16hz.

[David Ferguson]

According the the C125 specs (use C125 Dash Manager->Help->Topics Reference->Input Characteristics), the voltage range for the Digital and Speed inputs is 0-15 volts. They have a pull-up resistor for 3.3v (DIG) or 2.7v (SPD).

I think it's OK to connect them to the power side of a solenoid.

[bloit]

hi following up on this as I am trying to do the same.

I know that my solenoid is 20hz. When setting up the calibration, I assume the method is period. What I am stuck with is the calibration table. Would I have 2 entries. 0ms=0% and 50ms=100%??

[bloit]

also - what about samples? Should this be 1?

[David Ferguson]

hi following up on this as I am trying to do the same.

I know that my solenoid is 20hz. When setting up the calibration, I assume the method is period. What I am stuck with is the calibration table. Would I have 2 entries. 0ms=0% and 50ms=100%??

also - what about samples? Should this be 1?

OK - if you are trying to get the output in duty cycle %, then the calibration you list is probably correct (or depending on polarity, inverted 0ms = 100%, 50mS = 0%). Try it and see if the result looks reasonable.

If you click the help button on that window, you will find that it has this to say about the Samples parameter:
"Specifies the number of samples over which the measurement should be averaged.
Used with Frequency and Period Measurement methods.
Increasing this number reduces the update rate and may increase the accuracy of the measurement."

So start with Samples of 1, and then try increasing it if the data seems to be noisy or has some dropouts or spikes.

Good Luck!

[bloit]

Thanks. Will give that a shot!!!