MoTeC Global Forum

The wheel slip for traction control can be calculated from the digital inputs(drive speed and rolling speed) no problems, I use that and it works fine. There is also a way of “Deriving the wheel slip from either the aux volt or aux temp input”, how does that work?
What kind of signal/information is that?
How do I generate that information?
Can I generate that within any other Motec dash or “box”?
Can I connect the speeds to a SDL3 dash and generate the wheel slip value within the dash and send it thru an aux output from the dash to either aux volt in or aux temp in of the M4 ecu?

/J

Got this from support, looks like I would be able to do some tuning of the wheel slip thru the SDL3. Nice.

"Hello Joakim,
You can get slip as an analogue voltage input (option 3 or 4 in TC Slip Source).
SDL3 can calculate the slip automatically in Speed and Distance Setup. So what you can do is: receive wheel speeds into the SDL3, configure “Wheel Slip (Percent)” channel and use this channel to configure an Aux output. So at the end you should receive Aux output from the dash into the ECU.

Hope it helps. Please let me know if you need more information.

Thanks!

Yuri Khodos
MoTeC Research Centre
121 Merrindale Drive
Croydon South
3136 Victoria
Australia"

/J

Yuri Khodos wrote:You can get slip as an analogue voltage input (option 3 or 4 in TC Slip Source). SDL3 can calculate the slip automatically in Speed and Distance Setup. So what you can do is: receive wheel speeds into the SDL3, configure “Wheel Slip (Percent)” channel and use this channel to configure an Aux output. So at the end you should receive Aux output from the dash into the ECU.

I would really like to do this since my digital inputs are already tied up but Yuri's statment above doesn't quite make sense to me so if anyone with experience can confirm if it is possible. I have an ADL & a M48 pro.
This feature is not well documented in the M48 software but it seems to suggest that it expects to receive an analog voltage into either the Aux temp or Aux volt input that is proportional to wheel slip. Yuri's statment suggests we can generate this using an AUX out of the SDL3 for instance, However as far as I know an SDL3 (or the ADL that I have), cannot generate an analog voltage output - only PWM or Frequency?
So my question is, can this really be done? - if so please elaborate a little.

I will try PM'ing Yuri also and post a reply if I get any further info.

Not sure about the whole analog output from the dash, as I really haven't dealt with them much, though you are able to convert a PWM signal into a analog voltage though the use of a low-pass filter.

http://sim.okawa-denshi.jp/en/CRlowkeisan.htm

At the bottom of the page is a calcualtor for the design of such a circuit that you could place inbetween the two devices.

Cheers,

Thanks for your input MileyCyrus.
Yeah, I do know about RC filters but dont have a lot of practical experience with them. From my my initial calculations though, by the time I got enough filtering the ouput would be too slow. Since this wheel slip info is used for traction control the response needs to be fairly instantaneous.
That was some weeks ago when I last looked at that so I dont remember all variables that I tried but maybe someone with more experience would be able to get it to work better. There is some flexibility with the PWM frequency from the dash which I never played with. I assumed highest frequency would need less filtering.

Here is a reply from Yuri, I hope it might help someone else in the future...

To send slip data from the dash to the ECU you can set Aux output to Duty Cycle mode and use some kind of PWM to Voltage converter (lots of info on the internet). However you're probably right that the response time will not be good enough, so the better option in terms of update rate is to configure the Aux Output as frequency and use Frequency to Voltage converter (something like LM2917).

Regards!
Yuri

I will investigate F to V converters now and see if I can get something suitable.
Thanks Yuri.