AutomationDirect Modbus Error Codes

Topic: CM503

The following table provides reference information for Error Codes specific to the Modbus protocols:

AutomationDirect CLICK
AutomationDirect GS Drives
AutomationDirect Modbus (Koyo Addressing)
AutomationDirect SOLO Temp Controllers
AutomationDirect SOLO Modular Temp Controllers
Entivity Modbus RTU
Entivity Modbus Ethernet (H2WinPLC)
Modicon Modbus RTU
Modicon Modbus TCP/IP Ethernet

The error Message is displayed across the top of the panel screen.

Error Code P499 shows any Errors that are generated by the connected PLC. The P499 Error Message includes a four-digit hexadecimal value displayed at the end of the message. These values, specific to the Modbus protocols, appear in the table below.

For more information about error codes specific to C-More panels, see C-More Error Codes.

Note: The following PLC errors are monitored by the C-more panel. Active errors display on the panel screen. Refer to the specific PLC user manual for further details. These manuals are available online and for download. You can download user manuals at www.automationdirect.com.

Note: The PLC Mode Switch must be in (TERM) position in order for the C-more Panel to communicate with the PLC. Refer to the specific PLC user manual for further details. These manuals are available online and for download at www.automationdirect.com.

These PLC support ladder program multilevel Password protection.

This allows password protection without locking the communication port to an operator interface.

To invoke Multilevel Password, create a password with an uppercase 'A" followed by seven numeric characters (e.g., A1234567). Refer to the specific PLC user manual for further details. These manuals are available online and for download at www.automationdirect.com.

Modbus Exception Codes
Error Code	Name	Description
0x0001	ILLEGAL FUNCTION	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 not configured and is being asked to return registered values.
0x0002	ILLEGAL Data ADDRESS	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 the request will operate successfully (address-wise at least) on registers 96, 97, 98, 99. If a request is submitted with a starting register of 96 and a quantity of registers of 5, then the 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.
0x0003	ILLEGAL Data value	A value contained in the query Data field is not an allowable value for the server (or slave). This indicates a fault in the structure of the remainder of a complex request, such as that the implied length is incorrect. It specifically does NOT mean that a Data item submitted for storage in a register has a value outside the expectation of the application program, since the Modbus protocol is unaware of the significance of any particular value of any particular register.
0x0004	SLAVE DEVICE FAILURE	An unrecoverable error occurred while the server (or slave) was attempting to perform the requested action. When using a CLICK PLC, this error is commonly caused when Read Data from PLC and/or Write Data into PLC selections are checked for a password option in the CLICK PLC project. If C-more needs to read or write to the PLC, disable those selections.