Canopen communication, Command code – Lenze 931M-931W User Manual

Page 19

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CANopen communication

Parameter data transfer (SDO transfer)

Telegram structure

5

19

KHB 13.0003-EN

2.0

Command code

11 bits

4 bits

User data (up to 8 bytes)

1st byte

2nd byte 3rd byte 4th byte 5th byte 6th byte 7th byte 8th byte

Identifier

Data

length

Command

code

Index

low byte

Index

high byte Subindex

Data 1

Data 2

Data 3

Data 4

Error code

The command code contains the services for writing and reading parameters and the

information on the length of the user data.
Structure of the command code:

Write command code

Bit 7

MSB

Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

LSB

Comment

CS

0

Length

e

s

Write command / write request

0

0

1

0

x

x

1

1

CS: command

specifier

User data length

is coded in bits 2

and 3:

z

00 = 4 bytes

z

01 = 3 bytes

z

10 = 2 bytes

z

11 = 1 byte

Response to write command / write

response

0

1

1

0

x

x

0

0

Read command code

CS

0

Length

e

s

Read command / read request

0

1

0

0

x

x

0

0

Response to read command / read

response

0

1

0

0

x

x

1

1

Error command code

CS

0

Length

e

s

Error response

1

0

0

0

0

0

0

0

The command code specifies whether a value is to be read or written. The command code

also determines the data length (1 byte, 2 bytes, 4 bytes).

Write command code

4-byte data

(5th ... 8th

byte)

2-byte data

(5th and 6th

byte)

1-byte data

(5th byte)

hex

hex

hex

Write command / write request

(Send parameters to the drive)

23

2B

2F

Response to write command / write response

(Response of the drive controller to the write request

(acknowledgement))

60

60

60

Read command code
Read command / read request

(Request to read a parameter from the drive controller)

40

40

40

Response to read command / read response

(Response to the read request with the actual value)

43

4B

4F

Error command code
Error response

(The drive controller signals a communication error)

80

80

80

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