Energy Meter Manual

<Toc> <Ind> < 6. Modbus/TCP Communication Protocol>
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IM 77C01E01-10E
6.4.4 Response Error Codes
● When a response is returned
If an inconsistency is found in a request’s PDU, the PR300 ignores the request and returns
the following response.
Element
Number of bytes
Command
element
Hex value
MBAP Header
22 2 111
Arbitrary 0000 03
01 to 99
PDU
Unit ID
Function
code
Transaction ID
Protocol ID
Error
code
Number of
bytes
*The function code entered here is the request’s function code (in hex) plus 80 (in hex).
● Response Error Codes
Meaning
Funcation code error
Abnormal number of D registers
Error Code
01
03
02 Abnormal D register number
Cause
Function code does not exist.
Number of D registers out of the range is specified.
D register number out of the range is specified.
● When a response is not returned
In the following cases, the PR300 ignores the request and does not return a response.
• When no connection is established at the TCP/IP socket interface.
• When an inconsistency is found in a request’s MBAP header.
• When the communication with the serial communication device specified in Unit ID is
unusual.
Note: As a measure against the abovementioned problems, add a time-out process to the communication function or
program of the higher-level device.