Moxa Technologies EDR-G9010 Series, Руководство пользователя

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EDR-G9010 Series User Manual 185
Create a Modbus/TCP Profile
Modbus/TCP is a Modbus protocol used for communications over TCP/IP networks, connecting over port 502
by default. Modbus has also been experimentally used over UDP on IP networks, which removes the
overheads required for TCP. The following table shows the Modbus TCP frame format:
Modbus/TCP Frame Format
Description
Length Function
Transaction Identifier 2 bytes Synchronization between messages of the server and client
Protocol Identifier 2 bytes The value is 0 for Modbus TCP protocol
Length Field 2 bytes Number of remaining following bytes in this frame
Unit Identifier 1 byte Slave Address (255 is used for device broadcast information)
Function code 1 byte Defines the message type
Data bytes n bytes Data block with additional information
Name
Setting Description Factory Default
0 to 64 characters Enter a name for the protocol filter profile. None
Category
Setting Description Factory Default
Modbus/TCP Select the Modbus/TCP protocol. None
Function Code
Setting Description Factory Default
All, blank, common
function code
Select the function code or manually specify the function code.
The function code format is 0 to 255 and allows commas.
Refer to the
Common Function Codes table for a full list of
function codes.
None