Allen-Bradley MicroLogix 1200 Reference Manual page 403

Table E.7 Modbus Error Codes
(MicroLogix 1200 Controllers and MicroLogix 1500 1764-LSP Series B and 1764-LRP Processors only)
Error Error
Code
0 No error.
1 Function Code cannot Broadcast.
2 Function Code not supported.
3 Bad Command Length.
4 Bad Length.
5 Bad parameter
6 Bad File Type
7 Bad File Number
8 Bad Modbus Address
9 Table Write protected
10 File Access Denied
11 File Already Owned
(1) If Modbus Command is sent with a valid Broadcast address, then no exception reply will be sent for Error Codes 2 through 11.
(2) See Table E.4 on pageE-9 for valid Modbus memory mapping.
The controller responds to the Modbus command function codes listed in
Table E.6 below:
Table E.6 Supported Modbus Commands
(MicroLogix 1200 Controllers and MicroLogix 1500 1764-LSP Series B and 1764-LRP Processors only)
Command
Read Coil Status
Read Input Status
Read Holding Registers
Read Input Registers
Set and Reset Single Coil
Write Single Holding Register
Echo Command Data
Clear Diagnostic Counters
Set and Reset Multiple Coils
Write Multiple Holding Registers
Upon receiving a Modbus command that is not supported or improperly
formatted, the controller will respond with one of the exception codes
listed in Table E.7 below:
Description
The function does not support Broadcast.
The controller does not support this Modbus function or
subfunction.
The Modbus Command is the wrong size.
The function attempted to read/write past the end of a data file.
The function cannot be executed with these parameters.
The file number being referenced is not the proper file type.
The file number does not exist
The function attempted to access an invalid Modbus address.
The function attempted to write to a read-only file.
Access to this file is not granted.
Data file is already owned by another process,
Protocol Configuration
Function Code Subfunction Code
(decimal) (decimal)
1 -
2 -
3 -
4 -
5 -
6 -
8 0
8 10
15 -
16 -
Transmitted
Exception Code
none
nothing transmitted
1
3
3
1
2
2
(2) 3
3
2
2
Publication 1762-RM001C-EN-P
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