Exceptions; E.3 Exceptions - Michell Instruments Condumax II User Manual

APPENDIX E
E.3

Exceptions

A message request from the master will raise an exception response from the slave
(Condumax) if:
• the function code is unsupported
• the register quantity > 127 (0x007D)
• the register address is invalid
• the register address + the quantity of register is invalid
• an error occurred while performing the function
The exception response will contain the function code incremented by 80H and the
exception code.
The table below lists the codes supported along with an explanation of each code:
Code
01
02
03
04
Example of an Exception Response that reads a discrete inputs
Byte
1
2
3
4
The example above shows that the function code (02H) sent in the request has been
incremented by 80H with the exception code 01H included as the data within the
message.
72
Name
ILLEGAL FUNCTION
ILLEGAL DATA
ADDRESS
ILLEGAL DATA VALUE
SLAVE DEVICE
FAILURE
message generating an illegal function exception
Slave Address
Exception Code
Condumax II User's Manual
Meaning
The function code received in the query is not an
allowable action for the slave (Condumax).
The data address received in the query is not
allowable. More specifically, the combination of
starting address and number of registers is invalid
for the slave.
A value contained in the query data field is not an
allowable value for the slave.
An unrecoverable error occurred while the slave was
attempting to perform the requested action.
Meaning
Function
CRC
97081 Issue 28.1, July 2018
Value
01H
82H
01H
??