max sample rates of DASH command and others

[foca1]

haven't made a purchase yet, but curious to know what the max sample rates are of these BT, wifi, or USB set-ups. very intereseted in being able to troubleshoot with the datalogging, so looking to maximize sample rate, even if it means logging only one parameter.

thanks guys

[John@PPE]

I don't have a list of sample rates. It depends more on your vehicle's bus speed than the interface. Generally speaking a more expensive interface is faster than a cheaper interface.

[foca1]

ok, let's set some parameters then:

say i want to look at MAF as fast as possible with ScanXL pro on
2001 chevy suburban
Palmer USB OBD interface (OBDLink SX)

[Weston@PPE]

The sample rates depend on a lot of different factors. Usually the biggest factor is what protocol your vehicle communicates with (how fast it sends out data).

There are 3 main protocols that could be used -- CAN, J1850, and ISO. ISO is by far the slowest. If you were monitoring just 1 single PID, ISO might get you 5-6 PIDs/sec. J1850 could get 10-16 depending on the car (there are 2 types of J1850, one is faster than the other). If you're vehicle uses CAN I've seen as high as 30 PIDs/sec with an OBDLink.

I don't know the upper limit on CAN, I've tested with some of the expensive (and very fast) J2534 interfaces and seen 150+ PIDs/sec. When you're vehicle is using CAN your interface is much more important, if your vehicle uses J1850 or ISO a cheaper ELM interface works just as well.

A 2001 GM vehicle will use J1850, you could probably expect 12-14 PIDs/sec. I've got a GM car from around this time and I could test it for you if you'd like. Its been a while since I actually tested J1850 or ISO for this type of thing, so I'm not exactly sure on how close my estimates are.

[foca1]

great info. thanks. I am gonna go with the OBDlink, but are all OBDlinks created equal. There's SX, MX, Wifi, bluetooth

I am mostly looking for data rates as fast as possible, now and in future CAN vehicles i will own. so.... are they all the same, in this aspect. I'd imagine the BT would be the slowest... BTW, what kinda baud rates are we talking here, just curious?

[Weston@PPE]

The baud rates are something like this...

ISO: 8,192
J1850 VPW: 10,466
J1850 PWM: 41,XXX
CAN: 500,000

The OBDLink connects to your PC at 115200 baud (many ELM's, and even some older OBDLinks used 38400 baud). Even just the speed of the connection is slower than CAN, which is why you need the really expensive J2534 interfaces if you want it to be really fast.

For the  most part, any OBDLink should be comparable to any other OBDLink -- but there are a few differences between all of them. The WiFi versions can have some WiFi interference if there are a lot of other networks around, which can cause it to slow down a little bit. Bluetooth doesn't have this problem, and seems to be a very stable way to connect. The USB versions are also very stable. The OBDLink WiFi and OBDLink Bluetooth both have a USB port on them, if you decide later that you'd like to go that route. The SX is USB only, and the cable cannot be removed from the OBDLink. OBDLink MX is Bluetooth only.

The only differences in function between all of the difference OBDLink's is that the OBDLink MX supports GM's single wire CAN protocol, used for the low-priority systems like the Airbag module. This makes it the only OBDLink capable of doing enhanced diagnostics for the Airbag modules on those GM vehicles (~2007+) that used SW-CAN.

[mterveen]

what system do i need to support the abs commands for a 01 gm camaro?

[John@PPE]

We can't do that with DashCommand. Our ScanXL product will work, if you buy it with the enhanced GM package.

ScanXL is only Windows software.