Hello everybody! My problem seemd to be OS independent. iwmxsdk.dll and pipehandler.dll exports minimal number of functions enough to low-level work with wimax device. Sample of code connection to device: bool isPipeInit = PIPE_HANDLER_Init(); l5DispFuncs = PIPE_HANDLER_GetServiceDispatcherFunctions(); utilFuncs = PIPE_HANDLER_GetUtilityFunctions(); wmx_CtrlStatus_t ctrlSt = l5DispFuncs->pfnGetCtrlStatus(); if (ctrlSt==READY) { l5Status = l5DispFuncs->pfnConnectEx(L5_TARGET_DYNAMIC, &_MessagesHandler, &_EventHandler, 0, THREAD_ID_DEFAULT, &l5Conn); } Everything is OK here. But sending any command to device (such as NDNS_OPCODE_RF_ON) with l5DispFuncs->pfnSendReceiveMessage() retunrs WmX_ST_PIPE_FAILURE error. It seems some procedure like acquiring device is missing. Can anybody help me with this issue? Best regards, Anton Novikov.