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Example
Access to measurements from the sensor located at line 3 and address 32 of
unit n° 2.
A. Determination of the sensor address: (3 – 1) x 32 + 32 = 96.
B. Structure of the Modbus request:
-
Slave number for the unit (defined by COM 43)
-
Operating type (03 = read)
-
Address of the 1
st
-
Number of words to read
-
CRC
Thread: 0x02 0x03 0x08 0x30 0x00 0x01 0x86 0x56
Example
Access the status of the sensor located at analog input 5 of unit n° 2.
A. Calculation of the table index: 256 + 5 = 261
B. Request script:
-
Slave number for the unit (defined by COM 43)
-
Operating type (03 = read)
st
-
Address of the 1
-
Number of words to read
-
CRC
Thread: 0x01 0x03 0x0A 0x01 0x00 0x01 0xD6 0x21
Address Table
Supervision of the MX 43 sensors
All reading requests for the Modbus are done via function 3. The cartography
is shown below:
0
Slave address
management
2000
Standard address
management.
65535
word
word
01 = 0x0001
From addresses 0 to 1999, the Modbus
request address serves to select a slave.
The response consists of a data structure
corresponding to the slave configuration
outlined below.
From addresses 2000 to 65535 the
address management is typical Modbus
address management.
02 = 0x02
03 = 0x03
2000+96 = 0x0830
01 = 0x0001
02 = 0x02
03 = 0x03
2300 + 261 = 0x0A01
11- RS485 digital output
73
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