Anyone ever used an OBD II splitter? I have read a few things saying they are ok and others saying one of the 2 devices hooked up will have errors? http://www.obd2cables.com/products/product_info.php?cPath=21_29&products_id=85 http://www.carplugs.com/Product_view_Cables_2.html
I've had 1 on for about a couple of months now and I haven't had any problems. (I have dual aerorce gauges and a dashawk)
I have one but have been told by Diablosport that I should not use it with the DashHawk and the Predator. Something about priority of communications on the bus.
THANK YOU VERY MUCH......I have been looking high and low for something like this and almost gave up thinking they did not exist.
There are a couple/few issues. First is with the external/add-on device ID. I believe the OBDII spec (maybe it's the bus spec?) only defines a single device ID value for devices that plug into the OBDII port. They only expect a single device to be plugged into the port at any given time and didn't allow for multiple devices. The bus is a shared media like a lan cable. All the modules on the bus have a well known ID. Polls and responses have a destination and source ID in them (and sequence numbers, etc.). You look at every packet on the bus and see if it's for you. If it's not, you ignore it. So if you have 2 devices on the bus with the same ID, each will be picking up packets destined for either one. Might work unless you pick up something you don't understand and you don't handle it well. For example the DashHawk supports a number of DCx specific parameters (non-standard extensions) and the Predator doesn't. You're also going to be picking up responses that you never polled for (the other device did). and then there's the sequence numbers. Second thing is bus usage. Devices should be "well behaved" and not hog the bus for non-critical use (like scanning). I believe the DashHawk tries to limit itself to a max of 2%? bus utilization. If the Predator does the same and you have both plugged in you might be up to 4%? utilization now? I don't have any idea how busy the bus gets but you don't want to starve out the PCM and other modules when they're doing important stuff like running your engine. Another thing would be power draw. Certainly the Predator is sensitive to power draw and fluctuation on the bus/port (maybe not so much when logging). So it might work and it might not depending on the particular devices and load on the bus.
