Android Modbus Master/Client and Slave/Server for phones and tablets. The Modbus Monitor utility is simple but have many advanced features unmatched even by PC based standards. This is the only Modbus App in the Android store with three Apps in one!!! (Modbus Master, Modbus Server, and Sensors Server in Modbus TCP).
This utility works using Bluetooth, Ethernet, Wi-Fi, or USB Serial OTG ports.