2113 Encoding Serial Data

Apart from the details about protocols that are given in section 2.10.4, consideration has to be given to practical methods of transmitting the 'messages' around the data buses. Factors such as speed of transmission (bit rate), electrical interference and preservation of the integrity of messages has to be considered. Two of the methods currently in use are:

The differences between them are largely to do with the ways of representing the logic levels ( 0 and 1, or high and low) that are used in computing. In the NRZ method a binary code of 0,1,1,1,0,0,1 would be transmitted as shown in Fig. 2.16.

| | Trim level dependant | | Base vehicles

| | Trim level dependant | | Base vehicles

Fig. 2.14 The single wire BMW K bus

Diagnostic bus

Diagnostic bus

Diagnostic tester

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


Post a comment