Brent, thanks for getting back to me.
- Linear Position, brake pressure, steering angle, and throttle consume the the 8 analog ports
- Tire temps come in as 4 CAN addresses per wheel, each with 4 multiplexed 2-byte readings. 16 CAN addresses ideally to 64 channels but I'm guessing they can remain multiplexed and put on 16 channels.
- 4 wheel speed sensors
- ODBII data if testing an ODBII equipped car. It looks like both CAN and pre-CAN ODBII.
In the future we would expect to also do the late model.
[*] Some engine data from sensors. May include things like crankcase pressure with a dry sump scavanged sealed motor.
[*] Some minimal aero data to correlate with suspension data. The speeds aren't high but the spoiler is 6" tall at 80°.
[*] Brake rotor temps.
The wheel position sensors need to be connected to the analog ports because they need to be sampled at 500Hz. That could be reduced in a math calc to 100-200Hz but I'd like to capture the raw data. Steering angle from a string pot and brake pressure, depending on the car one or two. With a brake balance adjuster we have two brake pressure gauges which really help the driver reset the brake balance system before sessions; it would nice to know what is actually happening throughout the session.
The tire temp sensors are the big issue. The setup I'm looking at would have have 16 readings per tire multiplexed onto 4 CAN addresses. That would be 16 channels. I initially thought there was probably 8-bit addressing for the channels with maybe 128 or 192 available. That would have allowed demuxing the tire temp data into 64 channels. Ideally 4 wheel speed sensors to capture wheel spin in the rear and brake locking on the inside front.
Then there is the engine info which is in ODBII but not RCM2 compatible in pre-CAN cars. Presumably that also goes to virtual channels. In race cars without ODBII there will need to be an intermediate analog to CAN conversion, I'm guessing with some Ardunio boards. Unless there is a reasonably priced off the shelf unit.
Each situation may present its own problems. For example, knowing brake rotor temps may help in pad selection even if cooling isn't an issue.