Modbus Poll is a Modbus master simulator designed primarily to help developers of Modbus slave devices or others that want to test and simulate the Modbus protocol.
Exception errors are shown on the status line.
If you are a slave developer you can compose and send your own test strings in the "test center" and check the result from the slave in hex numbers.
OLE Automation for interfacing with Visual Basic, Excel etc. To interpret and show the Modbus data according to your specific requirements. E.g. edit data in Excel and then transmit the data to your slave device! Try the Excel example.xls installed with the program.
This app is the best.