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Appendix a, Can message protocol – AEM 30-2340 4-Channel Wideband UEGO AFR Controller User Manual

Page 19

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Page 19 10-2340 Rev 05 121012

Lambda values are scaled up by 10,000 to retain decimal points. For example, if a
value of 9,876 is received as a lambda value from a 4 CH UEGO controller, the actual
lambda value is 0.9876. Use the following equation to derive the actual lambda value:

Actual Lambda value = Lambda from a message / 10,000

The back pressure value is scaled up by 100. Use the following equation to derive the
actual back pressure value.

Actual back pressure value (PSIg) = pressure from a message / 100

APPENDIX A

CAN MESSAGE PROTOCOL

CAN 2.0b, 29 bit, 500 kBit/sec

8 data bytes/message

All multi-byte data packed big endian unless specified (most significant byte transmitted first)

All bits numbered with the LSB = bit0, MSB = bit7

Message ID:

0x0000001F

Source:

AEM 4 Channel UEGO set on MODE 1

Rate:

10ms continuous

Byte

Label

Data Type

Scaling

Offset

Range

0

Lambda 1

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

1

2

Lambda 2

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

3

4

Lambda 3

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

5

6

Lambda 4

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

7

Message ID:

0x00000020

Source:

AEM 4 Channel UEGO set on MODE 2

Rate:

10ms continuous

Byte

Label

Data Type

Scaling

Offset

Range

0

Lambda 5

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

1

2

Lambda 6

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

3

4

Lambda 7

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

5

6

Lambda 8

16 bit unsigned

.0001 Lambda/bit

0

0 to 6.5535 Lambda

7

Message ID:

0x00000021