But I'm not sure if this is modbus standard.ДЎ. My device will return a value which is out of range. Simple_modbus_example.zip Simple example to read and write holding registers of slave. Example Data (Object) Dictionary for Modbus parametersД¬onst mb_parameter_descriptor_t device_parameters = ,Д®rr = write_modbus_parameter(CID_DEV_REG0, ®ister_data) Д®rr = read_modbus_parameter(CID_DEV_REG0, ®ister_data) The device address, reg type, start address of register, number of registers defined as: `MB_DEVICE_ADDR1, MB_PARAM_HOLDING, 0, 1,` Per your request to read rite holding register: Hope it will help you to understand API and read your device data. The example has just one file and I removed as much as possible from there. I prepared the simplified example to read and write two holding registers of the device. So you do not need to go deeper to lower layer of Modbus port and read description of its parameters (`mb_param_request_t`). Additionally it allows to integrate this functionality with other components or networks adding abstraction object 'characteristic' with its CID - characteristic iD. The modbus controller is the common interface above Modbus API for all ports which allows to read and write any parameters of your slave device. In order to read registers from your device you can use command 'Read Holding Registers 0x03', and 'Write Multiple Holding Registers 0x10'. What do you mean it can be added to the stack if required? Is there a way for me to customize the underlying stack, or was that an offer to extend the existing library?

Modbus memory map