> I have not completely understood the difference between this two functions > (waitingdata/waitingdataex). > In my understanding, the waitingdata function gives the number of bytes that > are in the OS buffer, while waitingdataex gives the sum of bytes in the OS > buffer + bytes in the HW buffer? > Has anyone an advice in which case to use which function?
WaitingData working with OS level only. It return true if something is in OS buffers. Otherwise it waits until serial port receive some data. WaitingDataEX returns true, if some data laying in Synaser internal buffer. Otherwise it call WaitingData. In normal case you do not need WaitingData* at all! It is needed if you are using low-level access to serial port only. Better to use high-level reading functions (all with timeout parameter), they are calling waitingdata internally when it is needed. > And a second question if I may: > For the Recv. functions there is a timeout, example a:=RecvByte(50) > What happens during thin 50ms timeout? > When a byte is received during this 50ms, will it be contained in the > function result? 50ms is not reasonable timeout for reading from the serial port. RecvByte is very simple case, because it waiting for one byte only. So, if byte is in buffers, it is readed immediately. If buffers are empty, Synaser waiting until byte is received. Because you can wait forever in some cases, you must define timeout. So, it is maximum time for device reaction. After this time you can consider device as non-functional. So, preffered timeouts are in seconds. Look at stronger read function, like RecvString. It reading data in loop to Synaser internal buffer, until it found CRLF sequence. However all internal subsequent reads using your timeout again. So, it is "interpacket timeout", not "overall timeout". In other words, it is maximum time for silence on the wires. Typical usage of Synaser is call command to device and wait for reply. AT modem command, for example. You send some command into device, and you wish to read response. But what to do when device is not connected or busy? How long you wish to wait for response? 3 seconds? OK, then you call SendString with command, and next command will be RecvString with 3000ms timeout. It is all! You got response soon as possible, or timeout error after cca 3000ms and you know - device not responding. It is very simple. With RecvString, RecvTerminated and RecvBufferEx you can implement high-level reading for any protocol. Hope this help you. -- Lukas Gebauer. http://synapse.ararat.cz/ - Ararat Synapse - TCP/IP Lib. https://www.geoget.cz/ - Geocaching solution _______________________________________________ synalist-public mailing list synalist-public@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/synalist-public
