KeepAlive specify a value in milliseconds to check the OPC server accessibility

If the value of KeepAlive property of class TdOPCDAClient is greater than 0 dOPC internally creates a timer with an interval of given value in milliseconds. Each time the specified interval (KeepAlive value) passes dOPC sends a GetStatus request to the OPC server. If this GetStatus request fails in timer call (no response from OPC server) dOPC fires a OnTimeOut event.