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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » How does the BT device communicate to the ECU? pull or push?

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Author Topic: How does the BT device communicate to the ECU? pull or push?
Bob Stone
Member
Posts: 6
Post How does the BT device communicate to the ECU? pull or push?
on: September 6, 2021 (GMT)

Hello all.

So if I have the device logging all sorts of information, is the device sending a request to the ECU that the ECU then sends the info back ( so does this multi times per sec per sensor ) or does the ECU just flood out all this information and the device just listens for the info to display?

Someone I know mentioned to me that the “ECU” can get overloaded from polling to many sensors and got me concerned so want to see how the system works.

Thanks all
Bob Stone
Capp777
Member
Posts: 2994
Post Re: How does the BT device communicate to the ECU? pull or push?
on: September 6, 2021 (GMT)

Torque sends a valid command over
RS232 to the adapter where it is parsed
into a proper message to the ECU in the
protocol required. The ECU receives the
command and acts on it.

Torque is sending a request, waiting for the
response one at a time. While there are special
commands that could used by the ECU to
send multiple pids with a single request…
Torque is not really setup to use these
features. Nor does Torque just sit and wait
for one request with multiple reads.

If you had multiple displays using the same
pid address with different variables, I do believe
the multiple requests are reduced automatically
per read cycle.

The protocol used by your vehicle will affect the
number of pids you can read. The older protocols
were very limited where newer protocols like CAN
are capable of many more.
Bob Stone
Member
Posts: 6
Post Re: How does the BT device communicate to the ECU? pull or push?
on: September 6, 2021 (GMT)

So Have there been complaints of this causing ECU’s to overheat or break earlier from the constant load? Does my friend have a valid argument?

i.e. is it safer in general to limit my rate to 1 a sec or even less when I know it works at a rate of 10 times a sec with all my selected sensors for logging and dash? I need to rely on this car for a long time and am using this to monitor and head off any issues. I don’t mind doing the super slow rate, but would like to have the faster data just for more metrics.

Thanks about the detailed info on how it does communicate however!
Capp777
Member
Posts: 2994
Post Re: How does the BT device communicate to the ECU? pull or push?
on: September 7, 2021 (GMT)

I am just another long time user of
Torque Pro… not the developer but
I recommend checking your pid read
speed under Adapter Status icon and
keeping your polling within the number
reported.

Your display pids should only poll when
visible but your data logging might not
be complete depending the log settings
used.

I dont remember any threads about ECUs
overheating since I’ve been reading this
forum but maybe I missed it.

Remember your vehicles network is using
priorities to manage traffic flow so more
important systems get attention first.

But again to me, it doesn’t make sense to poll
more pids than your vehicles protocol can
handle. For example my older Fords were limited
to about 20 pids.
Bob Stone
Member
Posts: 6
Post Re: How does the BT device communicate to the ECU? pull or push?
on: September 8, 2021 (GMT)

Roger that!

Will do the test and just base it off that.

Thanks for the heads up on lack of people having ECU issues!
moreause
Member
Posts: 644
Post Re: How does the BT device communicate to the ECU? pull or push?
on: September 8, 2021 (GMT)

i would not be concern about breaking or overheating the line

is a communication line,

you won’t overheat the phone line because you talk to much lol

I tried ..not with torque… but with other software to overflow the bus..

in my case the only thing it did ..is the lost of all the data in the dash ….everything went normal when i stop

for the speed on sampling i would say just do some test

use the option to save value after all data are read … that will give you the minimum time you can go

standard value goes very fast ..30 to 50 ms range
custom pid tend to take more time for some reason 250 to 300 ms

and in my case i switch to another comm bus to get the seat belt status and revert back to the original bus that take almost a full second

so i have around 2 seconds for a full cycle

but if you stay to standard stuff you can use the .1 seconds log if you need to

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