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ADX definition questions

 
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cbernhardt



Joined: 18 Apr 2008
Posts: 85

PostPosted: Mon Apr 28, 2008 11:45 am    Post subject: ADX definition questions Reply with quote

I am using ScannerPro on a GM Ram Jet 350 engine. The injection system on this engine is an MEFI4a and uses a narrow band O2 sensor. I also have an LM-1 wide band installed but not connected to the MEFI4a controller. I would like to use my existing ADX file to log the wide band output along with all the other data from the engine. At this point I do not want to try to control A/F with the wide band, just log the voltage output.

The MEFI4a controller has several unused input connections including oil pressure, fuel pressure, and fuel temp. There are already definitions in the ADX file for these parameters and all three of these parameters display voltage so my thinking was that I could connect one of the analog outputs from the LM-1 to one of the unused input lines to the MEFI4a controller. The outputs from the LM-1 can be programmed to be from 0-5v or 0-1v.

Here is the definition for the oil pressure sensor:
<ADXVALUE id="77" idhash="0xDE6BB330" title="Oil Pressure / CAT Voltage">
<units>volt</units>
<packetoffset>0x35</packetoffset>
<range low="0.000000" high="4.980469" />
<alarms low="0.000000" high="4.980469" />
<digcount>2</digcount>
<outputtype>3</outputtype>
<MATH equation="X * 0.019531">
<VAR varID="X" type="native" />
</MATH>
</ADXVALUE>

Here is the definition for the fuel pressure:
<ADXVALUE id="102" idhash="0xCD521DDB" title="Fuel Pressure">
<units>volts</units>
<packetoffset>0x5A</packetoffset>
<sizeinbits>16</sizeinbits>
<range low="0.000000" high="4.999924" />
<alarms low="0.000000" high="4.999924" />
<digcount>2</digcount>
<outputtype>3</outputtype>
<MATH equation="X * 0.000076">
<VAR varID="X" type="native" />
</MATH>
</ADXVALUE>

Here is the definition for the fuel temp:
<ADXVALUE id="103" idhash="0xCD5202DB" title="Fuel Temp">
<units>volts</units>
<packetoffset>0x5C</packetoffset>
<range low="0.000000" high="4.999924" />
<alarms low="0.000000" high="4.999924" />
<digcount>2</digcount>
<outputtype>3</outputtype>
<MATH equation="X * 0.019531">
<VAR varID="X" type="native" />
</MATH>
</ADXVALUE>


I am assuming that the output from all these sensors to the controller are all voltages, so why does the MATH equation for these parameters show different multipliers?

Also, can you tell by looking at these definitions if the input data to the controller is, if fact, an analog voltage?

Thanks,
Charles
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Six_Shooter



Joined: 06 May 2007
Posts: 590

PostPosted: Mon Apr 28, 2008 5:45 pm    Post subject: Reply with quote

I don't see why you couldn't use one of those inputs to connect the WBO2 into, for datalogging purposes.

The multipliers will differ to show the correct "world" values, similar to that of a regular guage.

I would suspect that those would be voltage based inputs, as most inputs are, but what the range is, I can't tell. I would look up what those sensor would output and use that info to modify the .adx to suit.
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cbernhardt



Joined: 18 Apr 2008
Posts: 85

PostPosted: Tue Apr 29, 2008 4:38 am    Post subject: Reply with quote

Six_Shooter wrote:

The multipliers will differ to show the correct "world" values, similar to that of a regular guage.


Well, that is what I would think also, but is that what the MULTIPLIER actually does? For example, if you look at the Ignition Voltage definition:

<ADXVALUE id="76" idhash="0xDE6BA970" title="Ign Voltage">
<units>volt</units>
<packetoffset>0x34</packetoffset>
<range low="0.000000" high="25.500000" />
<alarms low="0.000000" high="25.500000" />
<digcount>1</digcount>
<outputtype>3</outputtype>
<MATH equation="X * .1">
<VAR varID="X" type="native" />
</MATH>
</ADXVALUE>

The multiplier is 0.1. Does that mean when the dash board is displaying an Ign Voltage of 13.5 volts that the voltage output from the controller is 135?
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Six_Shooter



Joined: 06 May 2007
Posts: 590

PostPosted: Tue Apr 29, 2008 6:46 am    Post subject: Reply with quote

Each value has 256 "steps" or "counts", so the ECM changes the voltage to these "steps/counts", to be transmittd on the datalink. SO the multiplier of .1, is moving the decimal over to the left one place to show a value of "13.5" on the gauge display, instead of "135".
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cbernhardt



Joined: 18 Apr 2008
Posts: 85

PostPosted: Tue Apr 29, 2008 8:46 am    Post subject: Reply with quote

Six_Shooter wrote:
Each value has 256 "steps" or "counts", so the ECM changes the voltage to these "steps/counts", to be transmittd on the datalink. SO the multiplier of .1, is moving the decimal over to the left one place to show a value of "13.5" on the gauge display, instead of "135".


OK, I think I see what you are saying.

The Fuel Temp voltage is an 8 bit value and is output in 256 “steps”. The “high” value is 4.999924, so 4.999924 / 256 = 0.019531 which is the value in the MATH equation.

Following the same logic - The Fuel Pressure voltage is a 16 bit value and is output (I assume) in 65536 “steps”. The “high” value is 4.999924, so 4.999924 / 65536 = 0.0000762928 which is approximately 0.000076, the value in the MATH equation.

So, for the highest accuracy, I should choose the Fuel Pressure input line?
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Six_Shooter



Joined: 06 May 2007
Posts: 590

PostPosted: Wed Apr 30, 2008 6:25 pm    Post subject: Reply with quote

It won't really matter which input you choose, because you will likely have to adjust the values and multipliers anyway.
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cbernhardt



Joined: 18 Apr 2008
Posts: 85

PostPosted: Sat May 03, 2008 3:11 pm    Post subject: Reply with quote

Six_Shooter wrote:
It won't really matter which input you choose, because you will likely have to adjust the values and multipliers anyway.


Well, I was able to connect the LM-1 to my controller and view/log the wide band data. In the process, I came across another question: Is there any relationship between the Range Low and High values and the MATH equation multiplier? In my case the voltage output from the LM-1 is from 1v to 2v. These voltages, when multiplied by 10, give the correct A/F ratio. I used the OilPressure/CAT voltage parameter in the ADX file and did not have to change the multiplier in order to get the correct voltage readings. As far as I can tell, modifying the Range Low and High values affects only the display in the Monitor mode.

Charles
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Six_Shooter



Joined: 06 May 2007
Posts: 590

PostPosted: Sat May 03, 2008 4:46 pm    Post subject: Reply with quote

cbernhardt wrote:
Six_Shooter wrote:
It won't really matter which input you choose, because you will likely have to adjust the values and multipliers anyway.


Well, I was able to connect the LM-1 to my controller and view/log the wide band data. In the process, I came across another question: Is there any relationship between the Range Low and High values and the MATH equation multiplier?


Not exactly. The multiplier is to change the counts into the proper range to be displayed. Basically it converts those 256 counts into a range that we are used to or can understand, like what we would see on a mechanical or electric in dash gauge. In other words teh mutiplier takes the raw hexidecimal data, and convertes it to a range that we can use as refernce to existing information, by use of the multiplier.

Quote:
In my case the voltage output from the LM-1 is from 1v to 2v. These voltages, when multiplied by 10, give the correct A/F ratio. I used the OilPressure/CAT voltage parameter in the ADX file and did not have to change the multiplier in order to get the correct voltage readings. As far as I can tell, modifying the Range Low and High values affects only the display in the Monitor mode.

Charles


That is correct, the range values only effect what is displayed on the "gauge" in the Scanner pro dash. This just makes it easier to view the data, by eliminating the uneeded range in the guage/display.
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