B&B Electronics MODSCAN32 - Manual - Manual (Page 66)

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MNetMon Description
Overview
What is MNetMon and why do you need it? First of all. MNetMon is a Win32 software application
designed to operate under Windows. It runs on Windows 95, Windows 98 or Windows NT. It uses all
standard Windows drivers, so no special hardware or drivers are required for its operation. MNetMon was
designed to provide a seamless interface between modbus devices and a TCP/IP network. It uses two PC
serial ports to monitor an active RS-232 modbus communications link, capturing data as it is exchanged
between the modbus master and modbus slave devices, and presents this data to other network PC’s using
the standard MBAP protocol as defined by Groupe Schneider.
MNetMon is an unintrusive data monitor. No changes are required in the existing modbus network.
MNetMon simply attaches to the network as shown and monitors character traffic. When it sees data points
transmitted in response to the Master’s poll, MNetMon copies the data to a local memory buffer accessible
to the network server. As data is refreshed, the buffer contents are updated. Any PC connected to the
TCP/IP network operating as an MBAP client may access the data buffer to obtain the data. Several MBAP
compatible network client applications are available, including ModScan32 and those custom VBA
applications generated using the modbuss OCX control from WinTECH Software.
MNetMon does not provide Write Access to the data. The PC’s Transmit lines are not connected, so
there’s no way the monitoring application can interfere with normal modbus communications. The integrity
of the original modbus link is maintained, and MNetMon does not have to be running in order for the
Master and Slave(s) to communicate. MNetMon, in effect, expands the number of modbus ports from any
given slave device to a virtually unlimited number. The port originally used to communicate with a single
Master device, may now service many asynchronous network connections without increasing the cost or
complexity of the existing link. Data from a single device may now be routed through-out a plant wide
network seamlessly and inexpensively.