The ModScanCE application operates as a MODBUS master device in either RTU or ASCII transmission modes. ModScanCE may be used to access and modify data points contained in one or more MODBUS slave devices connected to the PocketPC via a serial port or network. ModScanCE supports the standard MODBUS message types 01-06, 15 & 16.
ModScanCE provides menu selections that allow the user to select between the RTU and ASCII transmission modes and to define the connection parameters necessary to communicate with a modbus slave. The Setup, Connect, Select Protocol menu selection allows you to also specify the modbus time-out value and a delay timer that prevents the ModScanCE application from polling too quickly after receiving a slave's reply.
As soon as the ModScanCE application is connected to a communications port, it will begin polling for slave data using the parameters defined by the Setup, Data Definition dialog. Here, the user defines the slave address, point type, point address and number of data points to scan. The ModScanCE display will show the last retrieved values for the selected data points, as well as an indication of any errors which may occur in the poll request. A running count of the number of polls and the number of successful responses is also shown.
The Setup, DisplayOptions menu selection allows ModScanCE to display retrieved modbus data in a variety of formats, such as decimal, hexadecimal and floating point. ModScanCE may also be used to display the actual character data that is transmitted and received on the connection. This "View Traffic" mode of operation is useful for trouble-shooting cabling problems and intermittant time-out problems with a slave's response.
ModScanCE may also be used to verify write operations to a connected slave device. Seperate menu commands are available for exercising the single and multiple write commands. Each write dialog allows the user to specify the address and pattern to be written.