Function Codes; Read N Words - DigiTrace TCONTROL-CONT-03 Bedienungsanleitung

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-
Function
overview
number
0x03 or 0x04
0x06
0x10
v

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
Response (values in the Modbus float format):
01
12
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Function
Read n words
Write one word
Write n words
Please refer to Chapter 2.9 Error processing, Page 18 if the device
does not react to these functions or emits an error code.
Function
x03 or 0x04
1 byte
Function
0x03 or 0x04
1 byte
03 3100 0004
03 08 0000 41C8
Set point value
W1
(25.0)
Limitation
max. 32 words (64 bytes)
max. 1 word (2 bytes)
max. 32 words (64 bytes)
Address Number of
first word words
(max. 32)
2 byte 2 byte
Number of Word
bytes read value(s)
1 byte x byte
4AF5
0000 4120
Set point value
W2
(10.0)
Checksum
CRC16
2 byte
Checksum
CRC16
2 byte
4A9E