Campbell Scientific SDM-CAN Datalogger to CANbus Interface User Manual

Page 73

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Appendix D. Examples of CAN Data Frames and Data Encoding and Decoding

40bit data frame with one 32bit IEEE floating point value MSByte first

Rxed Bit order within bytes

87654321 87654321 87654321 87654321 87654321

Rxed Byte order

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Values

A

Bit order within values

32 25 24 17 16 9 8 1

Value byte order

Exponent

Mantisa

Start bit (parameter 09:) RH ref

40 33 32 25 24 17 16 9 8 1

Start bit (parameter 09:) LH ref

1 8 9 16 17 24 25 32 33 40

Start bit (parameter 09:) Right Hand reference.
1: SDM-CAN (P118)
1: 0

SDM

Address

2: 1

Time-quanta

3: 5

Tseg1

4: 2

Tseg2

5: 1000

ID

Bits

0..10

6: 0000

ID

Bits

11..23

7: 00

ID

Bits

24..28

8: 5

Rx,

real

IEEE4,

MSB

1st

9: 1

Start

Bit

No.

10: 32

No.

of

Bits

11: 1

No.

of

Values

12: 1

Loc [ value_A ]

13: 1.0

Mult

14: 0.0

Offset


Start bit (parameter 09:) Left Hand reference.
2: SDM-CAN (P118)
1: 00

SDM

Address

2: 1

Time-quanta

3: 5

Tseg1

4: 4

Tseg2

5: 1001

ID

Bits

0..10

6: 0000

ID

Bits

11..23

7: 00

ID

Bits

24..28

8: 5

Rx,

real

IEEE4,

MSB

1st

9: 40

-- Start

Bit

No.

10: 32

No.

of

Bits

11: 1

No.

of

Values

12: 1

Loc [ value_A ]

13: 1.0

Mult

14: 0.0

Offset

D-11

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