1. УКАЗАТЕЛЬ
//...
StreamType *Stream=new StreamType;
//...
Stream->Data.Request.Cmd = GET_DEVICE_ID_CMD;
num = Sync_Request(3+1, Stream);
//....

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2.ПЕРЕМЕННАЯ
//...
StreamType Stream;
//...
Stream.Data.Request.Cmd = START_FIRMWARE_UPGRADE_CMD;//
num = Sync_Request(3+1, &Stream);
//...