08 performs loop back test, Performs loop back test -8, Function – Yokogawa PR300 Power and Energy Meter User Manual
Page 102: Request (for nomal operation), Response (for normal operation), Example
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<Toc> <Ind>
< 6. Modbus/TCP Communication Protocol>
IM 77C01E01-10E
08
Performs loop back test
●
Function
This function code is used to check connection for communication.
•
For the format of response in the event of failure, see subsection 6.4.4.
•
The “0000” shown below (marked with an asterisk *) are fixed.
•
Any value can be selected for transmit data.
●
Request (for nomal operation)
Element
Number of bytes
Command
element
MBAP Header
2
2
2
2
2
1
1
Hex value
Arbitrary
0000
0006
01 to 99
08
0000
Arbitrary
PDU
Unit ID
Function
code
Transaction ID
Protocol ID
0000*
Transmit data
Number of
bytes
●
Response (for normal operation)
01 to 99
Element
Number of bytes
Command
element
MBAP Header
2
2
2
2
2
1
1
Hex value
Arbitrary
0000
0006
08
0000
Arbitrary
PDU
Unit ID
Function
code
Transaction ID
Protocol ID
0000*
Transmit data
Number of
bytes
●
Example
(1)
(2)
(3)
(6)
(4) (5)
(1)
(2)
(3)
(6)
(4) (5)
Send “1234” in hex to the PR300 to check the communication connection.
[Request] 000100000006010800001234
(1) “0001”: Arbitrary 2-byte data
(2) “0000”: Protocol ID=0000 (fixed)
(3) “0006”: Number of bytes
(4) “01”: Unit ID=01 indicating PR300
(5) “08”: Function code=08
(6) “1234”: Transmit data
The following response will be returned to the request above.
[Response] 000100000006010800001234
(1) “0001”: Arbitrary 2-byte data in the request
(2) “0000”: Protocol ID=0000 (fixed)
(3) “0006”: Number of bytes
(4) “01”: Unit ID=01 indicating PR300 (5) “08”: Function code=08
(6) “1234”: Transmit data
* Numbers in quotation marks are hexadecimal.