Schneider Electric VW3 A3 303 user manual Diagnostics

8. Modbus protocol

8. 6. Diagnostics (8)

Request and response:

Slave no.

08

Sub-code

Data

CRC16

Hi

Lo

Hi

Lo

Hi

Lo

1 byte

1 byte

2 bytes

2 bytes

2 bytes

Sub

Function

Request

Response

code

data

data

00

Echo

XX YY

XX YY

This function asks the slave to return the request sent by the master. The size

of the data is limited to 2 bytes.

01

Reinitialize channel

16#00 00

16#00 00

This function is used to reinitialize slave communication and, in particular, to

or

or

make it exit listen only mode (LOM).

16#FF 00

16#FF 00

03

Change ASCII delimiter

XX 00

XX 00

In ASCII mode, messages are delimited by the line feed character

XX = new delimiter

(LF = H'0A). This function is used to change this character.

04

Change to LOM mode

00 00

00 00

This function is used to force a slave to listen only mode (LOM). In this mode,

the slave does not handle messages which are addressed to it, nor does it send

any responses, except when the channel is reinitialized.

0A

Counter reset

00 00

00 00

This function resets all the counters responsible for monitoring slave

exchanges.

0B

Read the number of correct messages on the line without checksum error

00 00

Value of

counter

0C

Read the number of incorrect messages on the line with checksum error

00 00

Value of

counter

0D

Read the number of exception responses sent by the slave

00 00

Value of

counter

0E

Read the number of messages addressed to the slave excluding

00 00

Value of

broadcast messages regardless of type

counter

0F

Read the number of broadcast messages on the line regardless of type

00 00

Value of

counter

10

Read the number of NAK exception responses

00 00

00 00

The value read is always 0.

11

Read the number of slave not ready responses

00 00

00 00

The value read is always 0.

12

Read the number of messages received with character overrun

00 00

Value of

counter

The counters are unsigned words.

Example: Values 16#31 and 16#32 echoed by slave 4

Request and response:

Slave no.

Code

Subcode

Value of

Value of

CRC

CRC

Hi

Lo

1st byte

2nd byte

Lo

Hi

04

08

00

00

31

32

74

1B

29