ExceptionCodes (ENUM)¶
TYPE ExceptionCodes :
MODBUS exception codes.
- Attributes:
qualified_only- InOut:
Name
Initial
Comment
RESPONSE_SUCCESS
16#0
Everything OK
ILLEGAL_FUNCTION
16#1
The function code received in the query is not an allowable action for the server (or slave). This may be because the function code is only applicable to newer devices, and was not implemented in the unit selected. It could also indicate that the server (or slave) is in the wrong state to process a request of this type, for example because it is unconfigured and is being asked to return register values.
ILLEGAL_DATA_ADDRESS
16#2
The data address received in the query is not an allowable address for the server (or slave). More specifically, the combination of reference number and transfer length is invalid. For a controller with 100 registers, the PDU addresses the first register as 0, and the last one as 99. If a request is submitted with a starting register address of 96 and a quantity of registers of 4, then this request will successfully operate (address-wise at least) on registers 96, 97, 98, 99. If a request is submitted with a starting register address of 96 and a quantity of registers of 5, then this request will fail with Exception Code 0x02 “Illegal Data Address” since it attempts to operate on registers 96, 97, 98, 99 and 100, and there is no register with address 100.
ILLEGAL_DATA_VALUE
16#3
The value to be written is not valid
SLAVE_DEVICE_FAILURE
16#4
Unrecoverable error while performing the request
ACKNOWLEDGE
16#5
Notification of a Slave that a lengthy operation being started
SLAVE_DEVICE_BUSY
16#6
Notification of a Slave that a lengthy operation is in progress
MEMORY_PARITY_ERROR
16#8
Special error for function code 20, 21
16#A
Special error when using devices behind a gateway (Gateway misconfigured/busy)
GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND
16#B
Special error when using devices behind a gateway (Device does not respond)