Modbus RTU/TCP/ASCII Master ActiveX Control (Enterprise license) is a Development::Active X software developed by PLC control software. After our trial and test, the software was found to be official, secure and free. Here is the official description for Modbus RTU/TCP/ASCII Master ActiveX Control (Enterprise license): General specification for all our ActiveX Control - Support Windows 2000/Windows XP/Windows Vista which must have the VB6 runtime environment - Support most development environment which supports ActiveX or OLE design (Visual Basic/Visual C++/C#/VB.NET/VBA/C++ Builder/Delphi and so on) - Support to read and write Bit, Word, Long, Float, Double, Ascii char string, Wide char string. - Simple API interface for different protocol. - Able to create up to 16 protocols in one process. - Free manuals and sample. Feature for this product - Support Modbus RTU/TCP/ASCII Master which can communication with Modbus Slave - Able to connect up to 31 Modbus RTU/ASCII Slaves via one com port - Able to connect up to 31 Modbus TCP Slaves via tcp port - Supported function code(Hex): 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x0F, 0x10 - Let user to config the address range about function code, read points, write points - Support both Modbus address style and IEC61131 Syntax address style - Support both Dec address style and Hex address style - Runtime free Limitation for this product - The trial version of Modbus Master ActiveX Control is a fully functional version, but it has a limitation of only can be run half an hour after connect. If you want to run with no limitation, please order a register copy. you can download Modbus RTU/TCP/ASCII Master ActiveX Control (Enterprise license) free now.