Osi And Wireless Networks; Osi And Modbus - Banner Sure Cross DX80 Instruction Manual

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Sure Cross DX80 Network Basics

5.1 OSI and Wireless Networks

Although the SureCross wireless product is a proprietary wireless network and the various protocol layers are proprietary,
the wireless network can be compared to the standard seven layer model.
Instead of wires creating a connection, the 900 MHz or 2.4
GHz radio signal transmits the binary data, creating a radio
signal "link."
There are many other technologies and layers, but the most
important result is at the application layer where the data
exchanged between network nodes is used to monitor and
control events.

5.2 OSI and Modbus

Applying this analogy to Modbus RTU, the lowest layer is defined by RS-485. Modbus RTU functions at the data link layer.
The application layer is the PLC program on a PLC or the analogous control program on any host device.
Continuing with the OSI example, Modbus/TCP packages Modbus data packets inside the standard Internet TCP/IP
protocols. EtherNet/IP functions the same way. Data moves from the data link layer up to the top of the stack and provides
consistently structured data to use with a control program.
OSI Seven Layer + Modbus RTU Network Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
12
PLC Prog, DX80
Modbus RTU
RS-485
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Application Unique Application
Presentation
Session
Transport
Network
Analog, Discrete
Data Link
Physical 900 MHz Radio
OSI Seven Layer + Modbus/TCP Model
Application Control Program
Presentation
Session
Transport
Network
Data Link
Physical
Data
Modbus/TCP
Ethernet
Modbus RTU
RS-485