Energy Meter Manual

6-8
<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
22 2 2211
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
22 2 2211
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.