single wire temp sensor returned values

MMiskoe
Posts: 17
Joined: Sat Nov 05, 2011 2:42 am

single wire temp sensor returned values

Postby MMiskoe » Sun Nov 29, 2015 11:13 pm

Details on what I have:

Second Generation DL-1. 2 single wire (Autometer) temp sending units, 1000ohm pull down resistor (one for each sensor), 5V reference from the DL-1.

Returned values that are getting logged and displayed on a DASH 3 are in the 35 to 10 volt range. The logged voltage falls as the temp goes up as it should, but I never measured it below about 10V. The sensor is being supplied 5V, verified with a meter.

If the sensors are being supplied 5V (verified), how is it that the DL-1 is logging more than 5V?

The system used to work, then during the last race I was getting weird numbers returned so I created a gig outside of the car, used two new sensors and verified what is being logged and displayed with a meter.

Thanks
Matt

MMiskoe
Posts: 17
Joined: Sat Nov 05, 2011 2:42 am

Postby MMiskoe » Wed Dec 16, 2015 2:12 am

Bueller, Bueller, Bueller........

Support (D)
Posts: 74
Joined: Mon Aug 17, 2015 9:36 am

single wire temp sensor returned values

Postby Support (D) » Thu Dec 17, 2015 10:09 am

Hello there apologies for the long reply, OK so there are a few things we can check:

Firstly can you check that the 5V ref on the DL1 is reading 5V on the meter you have been using. (Before doing this test could you first verify the meter is reading correctly? Do this by testing on a known power source.)

Next can you send the run file from the DL1 that contains the strange values, then I can check for other contributing factors. Please send it to my email address which is: daniel@race-technology.com

Was there any incidents during the last race when the issue seemed to appear?

Lastly this gig you made to test the voltage readings did you use the DL1 5V ref to supply the sensors or was another power source used? Also did you see the same strange values from this test?

Answer the questions above it will provide me with a better understanding as to what the issue may be, when I have those we'll go from there.

Best regards,
Dan

MMiskoe
Posts: 17
Joined: Sat Nov 05, 2011 2:42 am

Postby MMiskoe » Fri Dec 18, 2015 3:24 am

The test rig does use the same wiring as the car, 5v is supplied by the DL-1. Used the same ground on the meter as the DL-1 is seeing.

Did verify the 5v from the DL-1 with a meter. Did not verify the meter against another meter or known source. I will do that.

Did not pay attention to when the issue started. Because the single wire sensors have a curve that gets weird at the cold end, I ignored odd readings at the start, or when the car was in the shop. I assumed I had a wiring issue. What caught my attention is how the DL-1 can be reading double digit voltage when the supply is no more than 5. No inverters or transformers here.

As for a file, why don't I create one that I can verify what the readings were with the meter so you can see the difference between the meter & the DL-1.


Thanks
Matt

Support (D)
Posts: 74
Joined: Mon Aug 17, 2015 9:36 am

Postby Support (D) » Fri Dec 18, 2015 9:14 am

Right OK sounds like something else is pulling the voltage up i.e. another power source going to the sensor.

Can you just double check that the sensor does not have another power source connected to it, the DL1 should be connected to the sensor as per the image in the link for a 1 wire sensor:

http://www.race-technology.com/wiki/ind ... WireSensor

If the sensor is already connected as per the 1 wire sensor diagram, can you tell me what pull up resistor was used to convert the resistance reading from the sensor to a voltage reading.

Also can you send me either the run file that the strange reading were first recorded on or simply make a new run file that demonstrates this. For the moment we'll leave the values from the meter alone until we verify the meter is functioning correctly.

Kind regards,
Dan


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