TCW210-TH-R1.2 - January 2018
Page 30
"alarm": "0",
"min": "---",
"max": "---",
"hys": "---"
}
}
},
"HTTPPush": {
"Key": "",
"PushPeriod": "300"
},
"hwerr": "",
"Alarmed": "0",
"Scannig": "",
"Time": {
"Date": "12.01.2018",
"Time": "16:10:26"
}
}
}
8.3.
MODBUS TCP/IP
MODBUS TCP/IP protocol is originally published by Modicon in 1979. It is used to establish
master-slave/client-server communication between intelligent devices. MODBUS TCP/IP is often
used to connect a supervisory computer with remote units in supervisory control and data
acquisition (SCADA) systems.
8.3.1.
Codes and answers
8.3.1.1.
Read Holding Registers (FC=03)
Request
This command is requesting the content of holding registers 100.
03 0064 0002
03: The Function Code 3 (read Holding Registers)
0064: The Data Address of the first register requested (0064 hex = 100)
0002: The total number of registers requested. (read 2 registers each 2 byte = 4
bytes)
Response
03 04 4296 8000
03: The Function Code 3 (read Analog Output Holding Registers)
04: The number of data bytes to follow (2 registers x 2 bytes each = 4 bytes)
4296 8000: 4 bytes value
All holding registers with float value are sent in big-endian.
In the example, the above value of 75.25 is sent.
Request
This command is requesting the content of holding registers 200.
03 00C8 0020
03: The Function Code 3 (read Holding Registers)
0064: The Data Address of the first register requested (00C8 hex = 200)
0020: The total number of registers requested (read 32 registers each 2 byte =
64 bytes)
Response
Summary of Contents for TCW210-H
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