ODB2 data logging

[nickpoore]

I recently obtained an ODB2 data cable for my data logger.

Unfortunately, it only appears to log data about once a second.

I spoke with the manufacturer, who said that this was dependant on the ECU, and beyond their control.
They said that on some ECU’s they log data more than 10Hz.

Does anyone have any experience with this, and does anyone know if the GM ECU can be altered to log the data more often?
Thanks.
Nick.

[silver]

what data are you trying to log?

I am using Spanky's aeroforce gauge to watch my IAT2's and it get's info directly from the OBDII plug and the temps change multiple times per second for sure........not sure if that helps.

[benyeats]

I don't know for sure but 1Hz sounds rather slow, on the other hand as Silver suggests it may not log all channels all the time.

Ben

[nickpoore]

The system is able to pick up the following data from my ECU:
RPM
speed
throttle_position
manifold_absolute_pressure
coolant_temp
intake_air_temp
mass_air_flow
engine_load
timing_advance

The RPM is less acurate that my current tach-counter (hooked up to Pin1 of the Atom dash.)
The Speed is lass acurate than my current GPS based solution.
The Throttle Position is less acurate than my current reader (that pulls the mV voltage from one of the two sensors in the drive-by-wire throttle pedal.)

Coolant Temperature is nice.
Intake Air Temp is nice.

Manifold pressure changes too quickly for 1Hz to be useful.
MAF changes too quickly for 1Hz to be useful.
Engine load changes too quickly for 1Hz to be useful.
Timing Advance changes too quickly for 1Hz to be useful.

It sounds like, from Silver's post, that the ECU is able to output at more than 1Hz.

Any ideas if there are settings on the ECU, or should I address this further with the Logger guys?

[DarthChicken]

It's the logger, the ecu will spit out data at something over 100hz.  I'm betting it's a limitation of the cable or port type.  If you lower the number of items being logged, it will speed up, but other than that I think you just have a slow logger. 

Does his plug into a laptop?  If it does, check your port settings, if it doesn't your stuck.

[silver]

I curse port settings LMAO, if it's a currently built product it should be USB and there should be drivers that come with it to make sure it runs perfect.  If it connects with anything older tech then usb, return it, it's not current technology.

[apollyon25]

ODB2 is hardly current technology, so your 9600baud serial port is more than adequate.

[benyeats]

[quote="apollyon25"]
ODB2 is hardly current technology, so your 9600baud serial port is more than adequate.
[/quote]

Beaten to it.  The 'USB' OBDII loggers are using USB in its serial port emulation mode.  OBDII has been around since approx the early 90s and the ECU in the Atom (any version) likely has its roots in many years old electronics. 

As for it being slower than the real time signals that the dash gets / throttle pedal generates of course it is!

Ben

[silver]

[quote="apollyon25"]
ODB2 is hardly current technology, so your 9600baud serial port is more than adequate.
[/quote]

what I meant was if it comes with a serial connector then you know it's OLD b/c even my 6 year old laptop doesn't have a serial connection any more, they've stopped adding them to a lot of laptops.........but anyways

[Terry Kennedy]

Beaten to it.  The 'USB' OBDII loggers are using USB in its serial port emulation mode.

That may or may not be an issue. The advantage to this is that Windows has built-in drivers for common USB/serial chipsets. So if you plug the device into a different PC, you get an automatic driver install, rather than having to hunt for the driver disc that came with the gizmo.

And just because it appears to the host as a serial port, doesn't mean it is limited to RS-232 speeds. The FTDI FT2232H (which just happens to be the first chip I thought of) can do serial speeds up to 12Mbit/sec (that's 20% faster than original Ethernet) or if used in other modes, up to 8 Mbyte/sec.

OBDII has been around since approx the early 90s and the ECU in the Atom (any version) likely has its roots in many years old electronics. 

As for it being slower than the real time signals that the dash gets / throttle pedal generates of course it is!

Depending on which particular OBDII signalling system is used by a car, you will get faster or slower data at the OBDII connector. The high-speed CAN bus on the Ecotec operates at 500Kbit/sec. Unfortunately, Brammo didn't connect it to the OBDII port on any Atom I've seen, but it is relatively easy to do so - you need to run a twisted pair of wires from the ECU to the OBDII port. (Brammo "stole" the existing CAN wires in the harness for the Masterlube power).

Remember, almost the entire dash of the Cobalt SS / ION Red Line that this engine was intended for run off the CAN bus. The only 2 exceptions that I've found are the boost gauge and the Check Engine Light.

[DarthChicken]

I can tell you that the logger I use, the one that comes with hptuners, logs a lot faster than 1hz.  The ecu, and obdii port on our cars is more than capable. 

[nickpoore]

It's good to know that the ODBII port is capable of supplying the data.
However, if I need to run cable to make this work; I'm more than happy to do so.  (I hate pulling cable, but it should not be too bad in this car...)

Thanks for the input guys.
Nick.

[positron]

Found this on the EFiLive forum so I think your product/vendor is laggy..

up to 24 channels: pid update rate is 10 Samples/second
over 24 channels: pid update rate is 5 S/s or less.

I'm using their V1, because that's what I had before, but have to program with their V2. The V1 is smaller and it stays with the car to datalog each session.