Networking via system bus (can), Transmitting parameter data telegram structure – Lenze EPM−T9XX Modular system User Manual

Page 188

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Transmitting parameter data

Telegram structure

8

Networking via system bus (CAN)

8.4

8.4.1

L

8.4−2

EDSPM−TXXX−9.0−11/2009

Identifier

Instruction

code

Index

Subindex

Data 1

Data 2

Data 3

Data 4

LOW byte HIGH byte

The instruction code contains the command to be executed and information about
the parameter data length. It is structured as follows:

bits 7

(MSB)

bits 6

bits 5

bits 4

bits 3

bits 2

bit 1

bit 0

Command

Command Specifier (cs)

Length

E

s

Write Request

0

0

1

0

00 = 4 bytes
01 = 3 bytes
10 = 2 bytes

11 = 1 byte

1

1

Write Response

0

1

1

0

0

0

Read Request

0

1

0

0

0

0

Read Response

0

1

0

0

1

1

Error Response

1

0

0

0

0

0

0

0

Instruction code for parameters with 4 bytes of data length:

4 bytes of data

(32 bits)

Command

hex

dec

Information

Write Request

23

35

Transmitting parameters to a node

Write Response

60

96

Node response to the Write Request (acknowledgement)

Read Request

40

64

Request to read a parameter from a node

Read Response

43

67

Response to the read request with the actual value

Error Response

80

128

Node reports a communication error

If an error occurs, the addressed node generates an Error Response".

In Data 4, this telegram always contains the value 6", in Data 3 it contains an error
code:

Command code Error Response

Data 3

Data 4

Error message

80

h

3

6

Access denied

5

Wrong subindex

6

Wrong index

Instruction code

Instruction Error Response"

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