Schneider Automation Modicon Quantum Ethernet Podręcznik Użytkownika Pobierz pdf (Strona 91)

Quantum Ethernet TCP/IP Modbus Application Protocol

840 USE 115 00 Version 1.0

The header is 7 b

tes lon

, and includes the followin

fields:

inv_id[2 b

tes] invocation id used for transaction pairin

proto_id[2 b

tes] used for intra-s

stem multiplexin

,default is 0 for Modbus

services

len[2 b

tes] the len field is a b

te count of the remainin

fields and

includes the dst_id and data fields.

The remainder of the pdu includes two fields:

dst_idx[1 b

te] destination index is used for intra-s

stem routin

packets.

(

currentl

not implemented

)

data[n b

tes] this is the service portion of the Modbus pdu, mb_pdu, and is

defined below

The service portion of the Modbus Application Protocol, called mb_pdu, contains 2

fields:

mb_pdu ::= { func_code[1], data[n] }

func_code[1 b

te] MB function code

data[n b

tes] this field is function code dependent and usuall

contains

information such as variable references, variable counts, and data offsets.

The size and content of the data field are dependent on the value of the function

code.

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Schneider Automation Modicon Quantum Ethernet Podręcznik Użytkownika Strona 91