Specification

Communication Format

Digital "0"

Digital "1"( BUS idle )

Resistance on CAN communication

High

Low

High

Low

Inside of ECM

IPM

CAN 2.0B

3.5V

1.5V

2.5V

2.5V

120Ω (20℃)

120Ω (20℃)

EMS

TCU

ABS

VDC

EPS

TPMS

Cluster

VGT

Air bag

4WD

IPM

CAN HIGH

68

87

6

14

3

5

2

3

30

5

10

CAN LOW

67

65

13

15

4

6

1

5

20

13

20

Signal Waveform & Data

Fig.1) CAN communication waveform

Monitoring CAN HIGH and LOW simultaneously is important in monitoring CAN communication waveform. When CAN HIGH signal rise to 3.5V and LOW signal drops to 1.5V - voltage difference between HIGH and LOW signal is 2V - at BUS IDLE state (DIGITAL "1") whose reference voltage is 2.5V, "0" is recognized. Besides, comparing HIGH and LOW signal if opposite waveform is detected with the reference voltage of 2.5V, Check if current cam signal transfers correctly.

Continuous "0"signal above 6BIT means the occurrence of error in CAN communication. 1BIT is easily distinguished as calculating the time when "SOF" (START OF FRAME) which notifies the start of frame occurs. Check if "0"signal above 6BIT is detected continuously when monitoring CAN communication waveform.

Яндекс.Метрика