Rockwell Automation 900 Temperature Controller Communications Functions - Series B - Manual (Page 71)

Publication 900-UM004D-EN-E - July 2010
Modbus Communications Procedure 4-13
Writing Undisplayed Parameters
It is possible to write the parameters that are not displayed due to display
settings as well as the parameters that are never displayed in the Controller.
Table 4.10
Name Description
Slave address The value from the command frame is entered as-is.
Function code This is the received function code.
When the function ended normally, the function code is left as-is.
When an error occurred, the hexadecimal value of H’80 is added
to the function code to indicate that the response is an error
response.
Example: Received function code = H’10
Function code in response frame when an error occurred = H’90
Write start address This is the received write start address.
Number of elements This is the received number of elements.
CRC-16 This check code is calculated with the data from the slave
address to the end of the data.
For details on the CRC-16 calculation, refer to CRC-16 Calculation
Example in on page 5-2.
Table 4.11 Response Code
Function Code Error Code Error Name Cause
H’90 H’02 Variable address error The write start variable address is incorrect.
The variable area number is incorrect.
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 write data is out of the setting range.
H’04 Operation error The Controller cannot write the data in its present operating
status.
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
H’10 — Normal completion No errors were found.