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Transmission and reception, I-bus (1-lead)

Transmission and reception, I-bus (1-lead)


The voltage difference between the lead and ground has only two values, approximately 0 and 5V. The information is coded so that different combinations of pulses between 0 and 5 V have different meanings.

The green bus lead is grounded internally in each control module via a 4 kΩ resistor. To send a zero the control module pulls the bus voltage up towards 5V. Voltage differences to ground less than 2.2 V are interpreted as a one and differences higher than 2.2 V as a zero. Note that a long series of ones is the same as if no message is transmitted.

The diagnostic tool is connected via the CANdi box to the 1-lead I-bus.

The 1-lead I-bus has a transmission speed of 33 kbit/s.