Question: using UDS / ISO-TP frames

Connectivity RealDash CAN
1

Question; I’m trying to control the cooling fan in the car, I have found the following CAN messages (ISO-TP frames) and am wondering if these can be used in the CAN XML, or sent via an action from RealDash.

its a request/response,
0x7E0 is the request ID
0x7E8 is the response ID

from what I can see to turn on the fan I need to send;

0x7E0: 10 08 2F 09 9B 03 00 40       <!-- the request -->
0x7E8: 30 00 00 00 00 00 00 00        <!-- the response (flow control - send data -->
0x7E0: 21 00 40 00 00 00 00 00        <- the request - remaining Bytes -->

essentially if I decode the ISO-TP message I get:
10 - single frame
08 - number of bytes ( full message = 2F 09 9B 03 00 40 00 40 )
2F - take control of the ECU input/output
09 9B - ID of the fan
03 00 40 - first bytes

30 00 00 00 00 00 00 00 - this is flow control - send all data without waiting

21 - Consecutive frameID
00 40 - remaining bytes

or has anyone else found a way to control “things” via can messages?

2

We control things via CAN all the time, but only with aftermarket ECUs, as they are much easier to control and configure.

There is an Action ‘Send CAN frame’, which can be used to send one frame at the time, so you could:

  1. Add a button to dash
  2. Go to ‘Input & Values’ and tap ‘Select Button Actions’
  3. Tap New Action
  4. Select Action Type ‘Send CAN frame’
  5. To ‘FRAME’ edit box enter 0x7E0: 10 08 2F 09 9B 03 00 40
  6. Click Done.
  7. Repeat from step 3 for a frame 0x7E0: 21 00 40 00 00 00 00 00

Now you have a button with two actions. Actions are triggered in order they are set for the button.

Remember that you do sending of CAN frames at your own risk. It is unlikely, but possible to send something invalid and brick your car. Aftermarket ECUs are much more resistant to ‘whatever’ flying around CAN bus, but stock systems may be very sensitive.

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