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Overview
12
35011984 02/2006
Modbus Plus Communication for Applications
Introduction Most Win32 applications that support serial Modbus communications can
communicate on a Modbus Plus network with the TSXCUSBMBP.
Virtual Serial
Port (VSP)
A Virtual Serial Port (VSP) is used as the mechanism for redirecting communications
from programs such as Concept, Unity, and ProWorx32 to the TSXCUSBMBP
adapter. The VSP presents the same interface as a standard serial port to the
software. As such it is indistinguishable from a physical serial port.
Modbus Plus
Communication-
Process
The Modbus Plus Communication process is described in the following table:
Illustration:
Routing Table A routing table similar to that used by Modicon's BM85 Bridge Multiplexer is used to
associate Modbus Slave IDs with 5-byte Modbus Plus routing paths. This allows the
application software to communicate with any Modbus Plus device within range on
a Modbus Plus network.
Stage Description
1 After the VSP is installed, it will create one serial port with the port reference (COM1-
COM12) defined in the TSXCUSBMBP Driver software.
2 When configuring the Modbus application software, this port reference for the VSP
is selected as the serial port for the application to use.
3 The TSXCUSBMBP Driver will then work like a Bridge Multiplexer to redirect serial
Modbus Plus messages onto a Modbus Plus network, but at a much faster rate since
no serial communications are actually taking place.
Virtual
Serial Port
Driver
TSX C
USB MBP
Driver
USB-MBP
Driver
Application
Software
USB
Controller
Windows XP
Operating System
USB-MBP
USB
Cable
Modbus Plus Network