AnalogX RCP MK2/MK3 CAN map still limited to linear sensors?

Q&A for AnalogX Analog to CAN interface. <a href="https://wiki.autosportlabs.com/AnalogX">Installation and Operation Guide</a>
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tecmini
Posts: 5
Joined: Sat Apr 28, 2018 5:02 pm

AnalogX RCP MK2/MK3 CAN map still limited to linear sensors?

Post by tecmini »

Is there still this same limitation listed under the AnalogX “Setting up for Race Capture” and does it apply to RCP MK2 & MK3 hardware when using AnalogX and non linear response sensors?:
Note - RaceCapture's CAN mapping features currently only supports sensors with a linear (straight-line) response. Sensors with a curved response, such as thermistors, will not work with the built-in direct CAN mapping.

If this still applies is there a work around other than replacing my 16 sensors with new linear sensors? I’m using typical GM Delphi coolant (TS10076) and air temp (25037225 and several other Delphi p/n’s) gauges now. I have their respective resistance charts/graphs but clearly not linear.

wizrd54
Posts: 23
Joined: Sat Apr 15, 2017 6:56 pm

Post by wizrd54 »

I don't have an Analog X, but I think the limitation over CAN is that you can only specify a scaling factor and offset to the raw CAN value to obtain something in engineering units. I haven't tried this before, but could you create virtual channels in the Lua scripting that take in the raw voltage over CAN and then transform it to a temperature?

With the analog inputs on the Race Capture you are also limited on the number of points to map a voltage to a temperature. In excel you could plot the curve and obtain a polynomial fit formula. Using this formula in a script you could then transform it from voltage to temperature.

I hope this helped. I think a more user friendly solution that could be added in a future software release would be to provide some mapping function after the CAN message is received in order to provide the functionality you are looking for.

tecmini
Posts: 5
Joined: Sat Apr 28, 2018 5:02 pm

AnalogX RCP MK2/MK3 CAN map still limited to linear sensors?

Post by tecmini »

This does indeed help Wizrd54 thank you. This is along the lines I was thinking I would have to go, basically doing this with virtual channels with better map data that the script functions can use. The 3 systems I’m cooling have very different temp thresholds. I got my RCP-MK2 yesterday (shout out to MikeD for helping me with that!) which will be used to control the pumps and fans via PWM. I’m using a RCP-MK3 for all display and data logging and all the other things the MK3 is great for. Using CAN via the AnalogX boards lets both the MK2 & MK3 get the sensor data instead of connecting them analog direct to the MK2 and having it try and transmit out via CAN. I’m hoping this will ensure the MK2 will be able to can keep up and handle the cooling tasks properly.

brentp
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Post by brentp »

We're considering a linear interpolation enhancement to the CAN channel mapping, similar to how it's done in the Analog channel mapping. No ETA on that, since it hasn't been scheduled with other priorities we have.

You might be able to do it in lua scripting in the meantime, or find a temperature sensor that has a linear output, like the Texense Liquid temperature sensor.

Thanks!
Brent Picasso
CEO and Founder, Autosport Labs
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