OBD-II port (how to run 2 gauges on one port)
 

Alright, before I had a ScanGauge, I was running a Greddy Informeter which displays just about everything but MPG. So when I bought ScanGauge II, it replaced my informeter. I have been a bit displeased with the ScanGauges hesitation to update the MPH/RPM and other engine performance stats so I ordered a OBD-II Y cable from OBD2cables.com, installed that had both devices hooked up everything seemed cool after install. Next day I take the car out for a drive to get to school and notice a problem immediately!

Both devices are fighting for the signal, depending on which one starts first that's who gets priority from the the system,
Trying to turn on the scangauge after the informeter has taken priority all I get is the "Connecting..." message then it will "connect" and just turn off with out displaying any stats (like the car is off).

So is this a limitation of the OBD-II system, my Honda ECU, or what?
Anyway I could run both at the same time? Maybe hardwire one or the other?

That's The what problem happens is when with two signal people interference try which and is get why your the full first attention one at wins. the same time.

Confusing :p

1 port - 1 device - otherwise you'll clash... Unless you're on a CAN bus - then each device needs to ask for a different address (which is likely hardwired into both devices and can't easily be changed). Your car isn't CAN - so that's not an option.

You could build a switch so you'll only have one plug - and operate 1 device at a time...

That's what I figured, smart ass. :p

C'moooon MPGuino!

I've heard of people running 2 SG's with the Y-cable before (I think on Priuses or Insights).

I wonder if the SG-II and a datalogger (Davis CarChip) would work.

BTW, what's CAN?

RH77

Nevermind -- looked it up. Next, how can you find out if your vehicle is CAN-patible :P

Controller Area Network, is the potential replacement for OBD-II.
However, it seems luxury auto companies are already looking beyond CAN to FlexRay.

FlexRay which offers faster and more reliable connections than CAN currently offers. FlexRay offers twenty times the speed currently supplied by CAN, by running parallel 10 megabit per second connections between the ECU and the car's actuators. At time of publication the main automotive backers of this new network system were BMW and Daimler Chrysler, with speculation from Volvo, Volkswagen, and Audi. However, Audi expressed interest in using it in their 2009 A8. The Japanese automakers such as Honda, Toyota and Nissan are also listed as associates of the FlexRay research development, but have concerns over the price of the new system when taking into consideration that they mainly offer economical cars. I am speculating that they will take a page from BMW and keep these new systems exclusive to their luxury divisions until the price drops, which is expected in 2010.

Interesting -- so would the interface remain consistent? I like the idea of OBD-II being consistent among models so folks can simply plug in an SG and test/scan any '96+ car sold in the U.S. (I'm sure with some exceptions). Would it likely be called OBD-III in the USDM?

RH77

Not sure on how to tell which cars are CAN, if I had to guess I would say 2000+ cars are CAN.

No clue about the next naming convention or prevalent technology, but I hope FlexRay wins. It sounds quite impressive on paper. Should lighten the load on cars too since it will require less wiring.

Another thing to look forward to in the future is the 42V car battery.

The SG has a data rate/refresh option. You may be on the slower setting, so check your manual.

Out of the box I set it on high, might not have been the best thing, but I think their own website says it updates every 2 seconds.

thebrad -

I went googling for an old fashioned "switch box" for OBD II cables and found this :

OBDII Interface Breakout Box
http://www.ecplaza.net/tradeleads/se..._breakout.html
http://image.ecplaza.net/offer/a/aut.../5059590_m.jpg
Pretty cool for development, but not what you want. I went here but couldn't find the switchbox that I thought might exist :

OBD2Cables.com
http://www.obd2cables.com/products/

Idea: If you have a cabling setup that converted to 25 pin serial port, then you could use a 25 pin switch box :

Probably not worth the effort.

CarloSW2

Thanks for the link CFG83, but like you stated probably not worth it. I'll just figure something else out.

More about CAN, it began being introduced in 2003/2004 and it's really not an OBD-II replacement from my new understanding it's really just a hub/router. The ECU sends a message to CAN then CAN assigns priority and sends it to the required assembly and OBD-II just regulates it. I understood it mainly because of my limited computer networking knowledge. But apparently the OBD naming convention will be kept, so I guess in the future we will have OBD-III to look forward to.

(FYI, just moving this thread into the new "Instrumentation" forum...)

How about the SGII's second port?
I remember reading someplace about daisy chaining 2 SGII's for more functionality.
No Idea if that helps or not.

I can try and chain 2 SGII's with a Ethernet cable if that helps any, but that's the only OBDII Device that I have so . . . ..

krousdb is doing this in his Prius (2 SGII's) daisy chained.

That would be a little less clean, but I'll look for a cat5 male to OBD-II female and try that out.