Vigilantplant TDLS8000, User Manual

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<11. Modbus>
11-1
IM 11Y01D01-01EN
11. Modbus
Modbus protocol can be used for TDLS8000 DCS communication. This section explains the
Modbus communication specifications that apply to the TDLS8000.
The main uses of Modbus communication on the TDLS8000 are shown below. Only a portion of
the TDLS8000 configuration function is supported.
• Checking measured values, I/O, and alarms
• Executing calibration, validation, and clock setting
• A portion of configuration functions (setting the current stream, inputting the temperature
and pressure)
11.1 Communication Specifications
The TDLS8000 can be used as a Modbus slave device. Modbus communication is possible by
connecting to a master device via Ethernet cable.
Communication standard Ethernet
Number of sessions (max.) 2
Protocol
Modbus/TCP
Port number 502
11.1.1 Message Structure
The communication message structure is shown below. The first seven bytes are the Modbus/
TCP header.
Bytes
1
Transaction ID
Modbus/TCP header
2
3
Protocol ID
4
5
Message length
6
7 Unit ID
8 Function
9
Data
:
l
Transaction ID
Data assigned by the master device to manage transactions. Slave devices simply return the
received value.
l
Protocol ID
Fixed at zero.
l
Message length
Data byte length after the unit ID.
3rd Edition: Jun. 10, 2016-00