Line pressure, pressure transducer

[gbaciak]

The one listed in the mega shift discription (http://www.msgpio.com/manuals/mshift/index.html)is no longer avalible from digikey, p/nMSP6907-ND .

Any sugestions on a different one?

I found this one on ebay http://www.ebay.com/itm/Pressure-transd ... 3a700f5456

Does anyone think this will work? It doesn't seem to have the same build quality, but were not monitoring anything too critical.

Let me know

Graham

[Bernard Fife]

Graham,

At first glance, it looks like it should work.

Lance.

[gbaciak]

Thats what I thought. It's bought and on its way soon. I'll be the guinea pig on this one.

[mikeymkll7mgte]

Im using two of those (100psi) to monitor oil and fuel pressure just to datalog them into MS. They have been in the car for almost 9 months now and no issues.

[gbaciak]

Im using two of those (100psi) to monitor oil and fuel pressure just to datalog them into MS. They have been in the car for almost 9 months now and no issues.

Thanks.... Makes me feel better about spend my 38 bucks... and I like the idea of the fuel and oil pressure idea

[tobmag]

Will any approriate sensor work, I cant find any calibration for this sensor in TS.
I have a 0-20bar sensor that is linear 0bar= 0,5v and 20bar = 4,5 volt.

BR//Tobmag

[Bernard Fife]

tobmag,

Unlike the temperature sensor, the pressure sensor is not calibrated in TunerStudio. Instead, you can either use the default response 'curve', or log the ADC directly (see: http://www.msgpio.com/manuals/mshift/V22tune.html#gi) and convert it using a formula in TunerStudio.

For your example: 0bar= 0.5v and 20bar = 4.5 volt.

There are 1024 ADC count to cover 0.0 to 5.0 Volts. So:
0.5V = 0.5/5.0*1024 = 102 ADC counts, and
4.5V = 4.5/5.0*1024 = 922 ADC counts.

So the pairs we have are:
(102 counts, 0 Bar) and (922 counts, 20 Bar).

The slope is then:
m = rise/run = (20 - 0)/(922-102) = 20/820 = 0.0244 Bar/count

The y-intercept is:
b = y - mx = 20 - 0.0244*922 = 20 - 22.488 = -2.488 Bar (this is the theoretical pressure when the Voltage is zero (if everything was linear).

So the pressure (in Bars) from the ADC count is:

Pressure(Bar) = 0.0244*ADCcount - 2.488

Then in the [OutputChannels] section of the mainController.ini file, create a line (using a test editor like notepad or notepad++) near the end like this:

Code: Select all

LinePressBar = {(0.0244*linepressure) - 2.488}, "Bar" ; line pressure for custom sensor in bars

(linepressure is the ADC count IF you have selected that in the menu linked above)

You can then create a gauge, add it to the datalog, etc. The gauge entry in the [GaugeConfigurations] section should look something like this:

Code: Select all

LinePressBar       = LinePressBar,  "Line Pressure",         "Bar",     0,   20,    2,   4,  18,  20,  0, 0

and the datalog entry should look like this:

Code: Select all

entry = LinePressBar,      "line",         int,     "%d"

See the existing entries for more examples.

If you wanted the output to read in psi, you would change the 20 in the above example to the corresponding pressure in psi (~290).

Lance.

[tobmag]

Hi Lance.

Thanks for the info but my programming skills are zero so I'm still lost.
Been using TS for a few years now for engine control so Im very familiar with all these things but changing Ini's etc is out of reach for me....

For MS3 there is calibration for the generic inputs http://www.msextra.com/doc/ms3/genericsensors.html

Would it be possible to get something like this since there is a huge variaty of sensors out there?

BR//Tobmag.

[Bernard Fife]

Tobmag,

This isn't programming at all. It is just text editing. I could add the required values to a new INI for you. Then it will be there for you to use very shortly (give me a day or so).

I could also add the values to the input parameters, but won't do this right away, and will only do it if fixing other stuff at the same time (since the 2.202 code is essentially frozen for release). When I do add it, I will let the user set two (voltage, pressure) points and then all of the above calculations will be done internally. Look for this in the 2.203 and 4.104 codes.

Lance.

[Bernard Fife]

Okay, here is the modified INI:

GPIO_MShift_2202b.ini

2.202 with added line pressure values

(193.9 KiB) Downloaded 886 times

Lance.