Internet PLC Forum

We ordered a custom smarttile PLC board with extra digital inputs and outputs (I2C). I tried using I2C_read and I2C read function to write or read the outputs and inputs but it did not work. How do I map the I2C to input/output addresses, so I can read and write to them?  The input address on the documentation provided is  0X21 The output address are  0X20, 0X22, 0X23 and 0X24. I would really appreciate any help to address this. Thank You.