How To Control The Frequency Converter; Function Codes Supported By Modbus Rtu; Modbus Exception Codes - Danfoss VLT Micro Drive FC 51 Design Manual

RS-485 Installation and Set...
Bus adress Bus register
0 1
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
19 20
29 30
8 8
Table 8.18
1) Value written in Modbus RTU telegram must be one or less than
register number. E.g. Read Modbus Register 1 by writing value 0 in
telegram.
8.8.9 How to Control the Frequency
Converter
This section describes codes which can be used in the
function and data fields of a Modbus RTU message.
8.8.10 Function Codes Supported by
Modbus RTU
Modbus RTU supports use of the following function codes
in the function field of a message.
Function
Read coils
Read holding registers
Write single coil
Write single register
Write multiple coils
Write multiple registers
Get comm. event counter
Report slave ID
Table 8.19
80
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®
VLT Micro Drive FC 51 Design Guide
PLC Register Content
1
40001 Reserved
40002 Reserved
40003 Reserved
40004 Free
40005 Free
40006 Modbus conf
40007 Last error code
40008 Last error register Read only
40009 Index pointer
40010 FC par. 0-01
40020 FC par. 0-02
40030 FC par. xx-xx
Function Code
1 hex
3 hex
5 hex
6 hex
F hex
10 hex
B hex
11 hex
MG02K202 - VLT
Access Description
Reserved for Legacy Drives VLT 5000 and VLT 2800
Reserved for Legacy Drives VLT 5000 and VLT 2800
Reserved for Legacy Drives VLT 5000 and VLT 2800
Read/Write TCP only. Reserved for Modbus TCP (p12-28 and 12-29 -
store in Eeprom etc.)
Read only Error code recieved from parameter database, refer to
WHAT 38295 for details
Address of register with which last error occurred, refer
to WHAT 38296 for details
Read/Write Sub index of parameter to be accessed. Refer to WHAT
38297 for details
Dependent on Parameter 0-01 (Modbus Register=10 parameter number
parameter access 20 bytes space reserved pr parameter in Modbus Map
Dependent on Parameter 0-02
parameter access 20 bytes space reserved pr parameter in Modbus Map
Dependent on Parameter 0-03
parameter access 20 bytes space reserved pr parameter in Modbus Map
Function Function
Code
Diagnostics 8
Table 8.20

8.8.11 Modbus Exception Codes

For a full explanation of the structure of an exception code
response, refer to 8.8.5 Function Field.
Code Name
1 Illegal
function
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Sub- Sub-function
function
code
1 Restart communication
2 Return diagnostic register
10 Clear counters and
diagnostic register
11 Return bus message count
12 Return bus communi-
cation error count
13 Return bus exception error
count
14 Return slave message
count
Meaning
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 register values.