Modbus Protocol; Function Codes - Danfoss ECL Comfort 210 Instructions Manual

Instructions ECL Comfort 210 / 310, communication description

7. Modbus protocol

The ECL 210/310 controllers are Modbus compliant devices.
The controller supports a number of public function codes.
The Modbus application data unit (ADU) is limited to 240
bytes.
Supported public function codes
03 (0x03) Read Holding Registers
04 (0x04) Read Input Registers
06 (0x06) Write Single Register

7.1 Function codes

Table 7-1: Function codes
Function
Read PNU
Write PNU
7.1.1 Modbus messages
7.1.1.1 Read read-only parameter (0x03)
This function is used to read the value of an ECL Comfort
read-only parameter number. Values are always returned as
integer values and must be scaled according to the parameter
definition.
Requesting a quantity of more than 123 parameters in
sequence gives an error response. Requesting non-existing
parameter number(s) will give an error response.
Request
Function code
Start PNU
Quantity N of PNU
Response
Function code
Byte count
PNU data value
Error
Function code
Error code
The request/response is Modbus compliant when reading a
sequence of parameters (read input register).
Danfoss District Energy
Function code
0x03 or 0x04
0x06
1 byte
2 bytes
2 bytes
1 byte
1 byte
2 bytes
1 byte
2 bytes
VI.LG.V3.02
Comments
Single PNU/register only
Single PNU/holding register only
0x03
0x0001 – 0xffff
0x0001 – 0x007B
0x03
2 – 246
0x0000 – 0xffff
0x83
1, 2, 3 or 4
DEN-SMT/DK
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