I now develop Modbus transportation compatible with Modicon RTU and I was going to use the opportunity of detecting IDLE state by the UART. But the duration value of IDLE character is fixed and equal one frame. It is unfortunate that this parameter can not be programmed, such as guard time for the smart card mode. This makes it impossible to implement this popular protocol, without using an external timer. Maybe something I do not understand, and the ability to modify the duration of Idle symbol exist? Thanks in advance for the answer.