How To Control The Frequency Converter; Function Codes Supported By Modbus Rtu; Modbus Exception Codes - Danfoss VLT DriveMotor FCP 106 Programming Manual

RS485 Installation and Set-...
Illustration 3.18 Mapping Input/Output Data in
Parameter 8-42 PCD Write Configuration
NOTICE
Gray lines are fixed, red are user-selectable.
Set up the following parameters in the frequency
converter:
Illustration 3.19 Mapping Input/Output Data in
Parameter 8-43 PCD Read Configuration
NOTICE
The motor current in parameter 16-14 Motor current is 32
bit. This mapping is only mapping the lower 16 bit, so
the maximum motor current readout is 327 A.
For higher Amp readout, use 32-bit readout.
Mapping a 32-bit parameter as 16 bit always accesses the
16 lower bits.
3.8.11 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.
3.8.12 Function Codes Supported by
Modbus RTU
Modbus RTU supports use of the following function codes
in the function field of a message.
MG03N202
Programming Guide
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
Read write multiple registers
Table 3.15 Function Codes
Function
Diagnostics
Table 3.16 Function Codes

3.8.13 Modbus Exception Codes

For a full explanation of the structure of an exception code
response, refer to chapter 3.8.5 Function Field.
Code Name
1 Illegal
function
2 Illegal data
address
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Function code
1 hex
3 hex
5 hex
6 hex
F hex
10 hex
B hex
11 hex
17 hex
Function Subfunctio Subfunction
code n code
8 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 slave 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.
The data address received in the query is
not an allowable address for the server (or
slave). More specifically, the combination
of reference number and transfer length is
invalid. For a controller with 100 registers,
a request with offset 96 and length 4
would succeed, a request with offset 96
and length 5 generates exception 02.
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