Rockwell Automation 900 Temperature Controller Communications Functions - Series B - Manual (Page 62)

Publication 900-UM004D-EN-E - July 2010
4-4 Modbus Communications Procedure
Error Codes
Table 4.2
Slave address The number specified in the command frame is entered as-is.
This is the unit number of the Unit returning the response.
Function code This is the received function code with the hexadecimal value
of 80 added to indicate that the response is an error response.
Example: Received function code = H’03
Function code in response frame when an error
occurred = H’83
Error code This code indicates the kind of error that occurred.
CRC-16 Cyclical Redundancy Check
This check code is calculated with the data from the slave
address to the end of the data.
The check code is 2-byte hexadecimal.
Table 4.3
End Code Name Description Error
Detection
Priority
H’01 Function code error An unsupported function code was received. 1
H’02 Variable address error The specified variable area address is out-of-range. 2
H’03 Variable data error The amount of data does not match the number of elements.
The byte count is not 2 times the number of elements.
The response length exceeds the size of the communications buffer.
The command code or related information in the operation command is
wrong or the write data is not in the setting range. 3
H’04 Operation error The write data contents are not allowed in the present operation mode.
·The Communications Writing parameter is set to OFF (disabled).
·Attempted to write to a parameter in Setup Area 1 from Setup Area 0.
·Attempted to write to a Protect parameter from other than the Protect
function group.
·AT execution in progress
·The command cannot be processed.
4