OBD2 port speed?

V

Vanne

Senior member
Dubai
Hi guys, i've got a question about the Z4 obd2 bus speed? MSS70

will polling the OBD2 bus provide /real/ time data? or will it be delayed? I know the canbus is faster, but is there any difference over the OBD2 port? the pinouts for the OBD2 plug on the BMW Z4 has canhi and canlo in the plug, is this the same as at the back of the speedo? *twisted pairs)

I am having issues getting data from the Canbus (CANHI/CANLO) on my racepak dash.

there is an OBD2 adaptor available, i wonder if that is a good way to solve this issue?
 
K line via OBD2 is pretty slow in comparison to the CANBUS, more so when you request multiple parameters.

There is no CAN at the OBD2 plug so you'll have to tap the twisted pair at the back of the cluster.

I have a Plex USDM100 connected to the CAN and I'm getting engine RPM, Oil temp, coolant temp, TPS, Torque, Brake status and wheel speeds in real time.
 
Wow, nice little unit. How did you configure the dash?. for the display? Stock ECU I'll assume? Mind if I have a look at your settings?
 
Yeah it's an awesome bit of kit. I have it mounted on the binacle in front of the main cluster.

You can configure whatever channels you like in the Plex device manager app. The MSS70 uses the same CAN IDs as the MSS54 in the E46 M3 so I just used those. I'll take a screenshot for you in a bit.
 
Thanks for the hex Id's. How about the dash itself, or it had a setting for E46? Is there also a setting for either 120 or 60ohms?
 
There's a preset for E46 M3 so you can use that. No need to worry about CANBUS termination as you're not the end of the bus.
 
When you pre select e46 M3, can you see the rest of the stuff that it populates? I am at a resort atm with my kids, so no access to my racedash software, but there are a hell of a lot of things it asks for. Selecting canbus by itself does nothing.
 
Yeah, it appears like in the screenshot I posted.

Either way, you need to ensure the bus speed is set to 500Kbit and is in passive/silent mode. Make sure no CAN filters are enabled.
 
Ohh.. that sounds like the stuff.. I'll have a look tomorrow. Thanks heaps. Mind if I chuck you a pm?
 
Martyn, (is that right or is it Martijn?) anyways, on that list, what is the visual colum? Also not sure what the factors colum is?

Seeing if I can pull the rest of the data from the bus today. Are you getting vehicle speed? Is that derived from wheel speed? Also not sure if your car is manual? If it is, does it know what gear your in? And is that info on the bus?

I’ve also got another general list of hex locations for other data that I’ll need, I’ll have a play around with that today. :thumbsup:
 
I'm english so it's just Martyn :)

The visual column just shows which of the 8 bytes of the CAN message is used. The factor is the math that's used on the raw hex to give you the actual value.

You can get actual vehicle speed (KPH) from CAN ID 0x153, Byte 1 Speed LSB, Byte 2 Speed MSB

No gear data available unfortunately.
 
hey Martyn, are you getting Oil Temp in Degrees C? struggling a little bit with oil temp, oil PX and water temp.. have you got the data lines for those 3? :D
 
The data lines are on the screenshot, with the exception of oil pressure, which isn't available.

Oil Temp = 0x545, byte 4, the value is an unsigned int, with a -48 offset.
Water Temp = 0x329, byte 1, the value is an unsigned int with the following calculation applied: [Temp in C = .75 * hex2dec(byte01) - 48]

So examples for both:

Oil temp raw (hex): 0x80
Oil temp decimal: 128
Oil temp converted: 128 - 48 = 80*C

Water temp raw (hex): 0x88
Water temp decimal = 136
Water temp converted: 0.75 * 136 - 48 = 54*C

Hopefully that makes sense :)
 
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