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

2 Protocol description
2.6

Function codes

Function-
overview
2.6.1

Read n words

Data request
Response
Example
12
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
number
0x03 or 0x04 Read n words
0x06 Write one word
0x10 Write n words
v
Please refer to Chapter 2.9 Error processing, Page 18 if the device
does not react to these functions or emits an error code.
This function is used to read n (n  32) words starting from a specific address.
Slave Function
address x03 or 0x04
1 byte 1 byte
Slave Function
address 0x03 or 0x04
1 byte 1 byte
Reading the W1 and W2 set point values (2 words each)
Address of first word = 0x3100 (W1 set point value)
Data request:
01 03 3100
Response (values in the Modbus float format):
01 03 08 0000
Set point value
Address
first word
2 byte
Number of
bytes read
1 byte
0004 4AF5
41C8 0000
Set point value
W1 W2
(25.0) (10.0)
Limitation
max. 32 words (64 bytes)
max. 1 word (2 bytes)
max. 32 words (64 bytes)
Number of Checksum
words CRC16
(max. 32)
2 byte 2 byte
Word Checksum
value(s) CRC16
x byte 2 byte
4120 4A9E