ConnectTimeout is an Integer property that indicates the maximum number of milliseconds to wait for successful completion of a connection attempt using the client. The default value for ConnectTimeout is 0, and indicates that the default timeout value for the protocol stack implementation should be used when establishing the client connection. 

The value in ConnectTimeout is used, along with properties like Host, Port, and ReadTimeout, when the IOHandler for the client is allocated in the Connect method. If the time period in ConnectTimeout has elapsed before successful completion of the Connect method call, an exception relevant to the TIdIOHandler is raised. 

Changing the value in ConnectTimeout causes the new value to be assigned to an existing IOHandler for use in subsequent Connect method calls. 

Please note that ConnectTimeout is not used in all TIdIOHandler descendants, and is provided for compatibility purposes. ConnectTimeout allows a client using a socket-based IOHandler, like TIdIOHandlerSocket or TIdIOHandlerStack, to access the protocol stack mechanisms used to control the connection timeout value. 

Use TIdTCPClient in end-user application; it publishes the public properties and events in the base class.

IOHandler 

Host 

Port 

ReadTimeout 

Connect 

TIdIOHandler 

TIdIOHandlerSocket 

TIdIOHandlerStack 

TIdTCPClient