context = ModbusServerContext(slaves=store, single=True)
It is common for beginners to confuse the "slave address" (which device am I talking to?) with the "register address" (which piece of data am I reading?). Witte Software ordering information - Modbus Tools modbus slave key
For general information on how these systems work, you can explore the National Instruments Modbus Introduction . context = ModbusServerContext(slaves=store
A thesis from Georgia Tech describes a version of Modbus that prevents "replay attacks" by requiring the master to generate a new secret key with the slave before a counter wraps. modbus slave key