2. MODBUS/TCP PROTOCOL
2 - 6
2.3.3 Diagnostics (Function diagnostics: 08h)
Use this register when performing the communication check from the client (controller). When a server
(servo amplifier) receives a Query Message, it sends the received data as a Response Message without any
changes to the client (controller).
(1) Message frame
Query Message
Transaction
Identifier
Protocol
Identifier
Length Field
Unit
Identifier
Function
Sub Function
Data
H L H L
16 bits
0000h
0006h
FFh
08h
00h
00h
8 bits
8 bits
Message field
Size
Description
Transaction Identifier
(Transaction identifier)
16 bits
Set any value.
Protocol Identifier
(Protocol identifier)
16 bits
Set "0000h".
Length Field (Message length)
16 bits
Set "0006h".
Unit Identifier (Unit identifier)
8 bits
Set "FFh".
Function (Function field)
8 bits
Set "08h".
Sub Function (Sub function)
16 bits
Set "0000h".
When a value other than "0000h" is set, a communication error occurs.
Data (Data)
16 bits
Set 2-byte length data.
Response Message
Transaction
Identifier
Protocol
Identifier
Length Field
Unit
Identifier
Function
Sub Function
Data
H L H L
16 bits
0000h
0006h
FFh
08h
00h
00h
8 bits
8 bits
Message field
Size
Description
Transaction Identifier
(Transaction identifier)
16 bits
Transaction Identifier received from the client (controller) is copied and returned.
Protocol Identifier
(Protocol identifier)
16 bits
The value "0000h" is returned.
Length Field (Message length)
16 bits
The byte length from Unit Identifier to Data is returned.
Unit Identifier (Unit identifier)
8 bits
Unit Identifier received from the client (controller) is copied and returned.
Function (Function field)
8 bits
When the message was received without errors, "08h" is returned.
Sub Function (Sub function)
16 bits
The value "0000h" is returned.
Data (Data)
16 bits
The data set in the Query Message is returned.
Summary of Contents for MELSERVO-JE MR-JE-C
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