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5. Modbus Applications
The ALM-06-WF include a Modbus port that allows you to access terminals data
via Wi-Fi and communicates using a master-slave technique in which only one device
(the master) can initiate transactions (called queries). The other devices (slaves)
respond by supplying the requested data to the master, or by taking the action requested
in the query.
Most SCADA (Supervisor Control And Data Acquisition) and HMI software can
easily integrate serial devices via the Modbus protocol, such as Citect, ICONICS, iFIX,
InduSoft, Intouch, Entivity Studio, Entivity Live, Entivity VLC, Trace Mode, Wizcon,
Wonderware, etc.
For Android Device, a freeware HMI Modbus is easy to use.
5.1 What is Modbus TCP/IP?
Modbus is a communication protocol developed by Modicon in 1979.
Different versions of Modbus used today include Modbus RTU (based on serial
communication like RS485 and RS232), Modbus ASCII and Modbus TCP, which is the
Modbus RTU protocol embedded into TCP packets.
Modbus TCP is an internet protocol. The protocol embeds a Modbus frame into a
TCP frame so that a connection oriented approach is obtained thereby making it reliable.
The master query's the slave and the slave responds with the reply. The protocol is
open and hence highly scalable.
ALM-06-WF User's Manual
ALM-06-WF
User's Manual (Rev1.0, Feb./2019) ------------- 31
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