Chapter 6 Communication Mode
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6.3.5 Error detection in modbus master mode
TRNS 9 command can check the execution results with t-parameter and the details with s parameter. If error flag
(t+2) of t parameter comes ON after TRNS 9 command execution, some type of error has occurred.
Return code area
The TRNS 9 command execution results and the executed command (H80) are stored in return code area (s
parameter head word).
Exception result H00 means operation is completed properly. Other values are error code as below table.
Error code
The types of errors are divided into four categories. (Please refer to section “A.5 TRNS 9 Return code” for details
on EH-SIO hardware errors and error detected by CPU module.)
Table 6.12 Modbus master mode errors detected by EH-SIO
Issued command is not supported.
Initializing command is executed more than twice.
The parameter of initial setting is wrong.
The port has not been initialized yet.
The parameter value or the number is wrong.
The EH-SIO input buffer is full with receiving data.
Table 6.13 Modbus master mode errors detected in communication
EH-SIO detected parity error in response.
EH-SIO detected framing error in response.
EH-SIO detected overrun error in response.
EH-SIO detected abnormalities in validity of the check code of a
response.
Receiving of a response was not completed within the time
specified by EH-SIO.
Transmitting timeout
error
EH-SIO did not complete transmission of query within set time
interval. (Monitoring time is fixed by the system. It cannot be
changed.)
Error message
response receiving
Error message response was received.
(Example: Modbus exception response receiving, etc.)
Received data format is wrong.
Send data (query) format is wrong.
If exception response is received, error code will be H90. In this case, the exception code (refer to P6-38) is stored
in receiving data area.
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