MoTeC Global Forum

I'm trying to display Ground Speed on my dash in Practice Mode, but what's being displayed is WAY lower than it should be (e.g., 58 mph when I'm actually going 125 mph).

My "wheel speed" sensor is a Hall sensor that reads the bolts on the CV joint casing and is fed into the ECU as the "Digital In 1 Speed" sensor. We have set up the speed calibration within the ECU as MPH per the documentation and we ARE getting the correct speed logged, as displayed within I2. However, when I try and generate the "Ground Speed" channel within Dash Manager using the ECU "Digital In 1 Speed channel as its input, it displays on the dash improperly as described above.

My settings are:
Calculations=>Speed and Distance...=>Ground Speed tab:
Method: Left
Left Input Channel: Digital In 1 Speed (calibrated to come in from ECU as mph)
Generate Ground Speed: Ground Speed

I then have my Display Setup set to show Ground Speed (in mph) on the line 1 of the bottom display, units=mph with a filter=250 msec.

Incidentally, I also have similar errors in my Gear Detection setup which I believe is related to this problem. In that case, I am using Method=Speed/RPM and am calculating it using Ground Speed for the Speed Input Channel along with the Engine RPM for the Engine RPM channel and all the proper speeds for the gears at 1000 RPM. The result is that the gear shown on the display is way lower than it should be (e.g., 2 when I'm in 3rd, 4th or 5th). Again, I'm pretty sure it's the Ground Speed channel that's being generated improperly.

Any help would be most appreciated!

please email some data and the config to:

support@motec.com.au

Regards

Jamie

Jamie,
I emailed a .zip file several days ago with data & config, did you get it? Sometimes they get caught in firewalls...Thanks!

I am away at present, and have forwarded your email to be looked into before I get back.

-Jamie

Ok, I have looked into this anyway...

here is some info for you.

1) your practice mode in that data does not have a speed configured



2) your ground speed setup is not a recommended method. You appear to have only 1 wheel speed input which is fine. You have assigned that input speed to drive speed, this is also ok. You have also assigned that same input to ground speed, which again is also ok. But you have added drive speed as the right input to your ground speed calculation. This means that the ground speed is calculated with dig 1 and a calculation of dig 1 as drive speed. I wouldnt recommend this as I am not sure how it would actually work.



Let me know if this helps?

regards

Jamie

Hi Jamie,

Actually none of that helped. Here's the excerpt from the email I sent support with the .zip file:

"I misspoke – the ground speed is being displayed on the Race tab of the Display setup, not the Practice tab. I also tried messing around with my Speed calculation by using the Fastest method between Dig In 1 Speed and Drive Speed, but that didn’t make any difference."

So what that meant was that I tried messing with the Drive Speed tab only after my initial attempt at setting up Ground Speed didn't work. Here is how my initial setup looked (note Drive Speed is OFF with the same result, that being a display of 58 MPH when the logged speed was 129 MPH):

Display Setup:


Ground Speed Tab:


Drive Speed Tab:


Any other ideas?

Thanks,
Bruce

Hi Bruce,

Looking at the config that you sent to us on support. The config shows that on the practice tab you have an overide for maximum straight speed. Do you have another config which has ground speed displayed on the practice tab that you have not sent us?

In the M4 software, have you calibrated your speed channel to be in Mile/Hour, or Kilometer/hour?

One think to keep in mind is that as we dont send channel units between devices. By default our templates assume that you are sending metric channels.

So if you calibrate the speed in Km/h in the M4, then display it in Mile/Hour, all will be fine.

If you calibrate your speed in Mile an hour in the M4, then when you try to use it as Mile/hour in the dash, it will do a second Mile/hour convert from Metric to imperial.

So in this instance, if you are doing 120 mile/hour according to the wheel speed sensor, you will see only 74 mile per hour on the ADL.

That may be your issue.

Also, do you have any logging from your M4 to show what it believes the dig speed 1 channel is compared to the ADL Dig speed 1.

-Jamie

OmarK wrote:Hi Bruce,

Looking at the config that you sent to us on support. The config shows that on the practice tab you have an overide for maximum straight speed. Do you have another config which has ground speed displayed on the practice tab that you have not sent us?

No, I explained in the post just before yours that the Ground Speed in question is on the Race tab, not the Practice tab (that was an error on my part); right now we don't use the Practice tab as we don't have a mode switch. Sorry about that.

JamieA wrote:In the M4 software, have you calibrated your speed channel to be in Mile/Hour, or Kilometer/hour?

One think to keep in mind is that as we dont send channel units between devices. By default our templates assume that you are sending metric channels.

So if you calibrate the speed in Km/h in the M4, then display it in Mile/Hour, all will be fine.

If you calibrate your speed in Mile an hour in the M4, then when you try to use it as Mile/hour in the dash, it will do a second Mile/hour convert from Metric to imperial.

So in this instance, if you are doing 120 mile/hour according to the wheel speed sensor, you will see only 74 mile per hour on the ADL.

That may be your issue.

Also, do you have any logging from your M4 to show what it believes the dig speed 1 channel is compared to the ADL Dig speed 1.

-Jamie

Hi Jamie,

This sounds like it may be the cause. I have calibrated the Dig In 1 Speed as MPH within the M48 Dos software. Within I2, I have mapped it to a channel named Vehicle Speed whose units are in MPH as well, see here:


When looking at the log in I2 it shows 128 MPH as expected. However the dash itself shows the lower speed at the corresponding spot on the track. In ADL, Ground Speed ON THE RACE TAB is set up with Units = MPH, see here:


If this is then causing it to be converted a second time, what SHOULD the units be set to in the display setup? I don't see an option in the dropdown list for "no conversion".

Thanks!