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2
Protocol description
2.6
Function codes
The functions described in the following are available for the readout of measured
values, device and process data as well as to write specific data.
Function- overview
Function
number
0x03 or 0x04
0x06
0x10
Please refer to Chapter 2.9 Error processing, Page 18 if the device does not react to these
functions or emits an error code.
2.6.1
Read n words
This function is used to read n (n ≤ 32) words starting from a specific address.
Data request
Slave
address
1 byte
Response
Slave
address
1 byte
Example
Reading the W1 and W2 set point values (2 words each)
Address of first word = 0x3100 (W1 set point value)
Data request:
01
03
Response (values in the Modbus float format):
01
10 | nVent.com
Function
Read n words
Write one word
Write n words
Function
x03 or 0x04
1 byte
Function
0x03 or 0x04
1 byte
3100
0004
4AF5
03
08
Number
Address
of words (max.
first word
32)
2 byte
2 byte
Number of
Word
bytes read
value(s)
1 byte
x byte
0000
41C8
Set point value
W1
(25.0)
Limitation
max. 32 words (64 bytes)
max. 1 word (2 bytes)
max. 32 words (64 bytes)
Checksum
CRC16
2 byte
Checksum
CRC16
2 byte
0000
4120
Set point value
W2
(10.0)
4A9E
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