QModMaster is a free and open-source Qt-based Modbus master based on libmodbus (see Libraries below). QModMaster is licensed using the LGPL and includes a bus monitor for examining traffic on the bus.
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. With the multiple document interface you can monitor several Modbus slaves and/or data areas at the same time. For each window you simply specify the Modbus slave ID, function, address, size and poll rate. You can read and write registers and coils from any window. If you want to change a single register, simply double click the value. Or you can change multiple registers/coils. Multiple data formats such as float, double and long with word order swapping are available. 2b1af7f3a8