ModScan is a Windows application designed to operate as a MODBUS Master device for accessing data points in a connected PLC compatible slave device. It is designed primarily as a testing device for verification of correct protocol operation in new or existing systems. MODBUS data points, coils and registers, may be read and/or written from the ModScan application using MODBUS Commands 01-06. The basic operation of the application is depicted in the typical Windows display below:
The specified MODBUS slave device is polled by the ModScan application on a cyclical basis specified by the user. Any address supported by the device may be scanned and the associated values listed on the bottom of the display. Communications errors or Exception Responses returned by the slave device are listed on the ModScan status line. Writing a specific data point is as simple as double-clicking an address/value combination and entering the desired value in a pop-up dialog:
Menu options allow register values to be displayed in either decimal or hexadecimal notation. Options are also available to select either the RTU or ASCII transmission modes. One additional feature of ModScan is the ability to display the actual serial data traffic between the master and slave devices as it occurs:
Last Updated: December 29, 1996
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