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06/17/10 14:58
Modified:
  06/17/10 15:02

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#176734 - Don't blame the driver or the adapter
Responding to: Andy Neil's previous message
The driver was not installed properly. The user is to blame. Buying a cheap adapter is the fault of the user. Finally, actual data can be lost because of the USB Host Controller that resides on the PCI Bus within the motherboard itself. This is mainly the fault of the advent of USB as there was a discussion a long while back where USB requires a "HUGE" FIFO. What happens is that if the user's program does not "sit" on the USB Host controller's buffer the host controller will over write it's own buffer causing records of data to be lost as the host controller does not have infinite space. So, if the user's program does not poll the serial port fast enough, data is lost. One can account for it by having a large hardware FIFO and increasing the "latency" so that the USB Host controller does not have to continuously service the FTDI chip. There is another method, but one cannot easily perform it with the use of an FTDI chip. In essence, these converters are a generality of a serial port and cannot be made to consistently give correctness for a given application. If someone were to use these converters blindly, do not expect your design to work perfectly. As pointed out before, just because it works, doesn't mean that it is correct.

List of 23 messages in thread
TopicAuthorDate
Serial Port monitor software      David Good      06/15/10 13:42      
   Docklight      Rob Klein      06/15/10 14:00      
      I use...      Michael Karas      06/15/10 20:49      
   monitor and control      Juergen Christoph      06/16/10 02:14      
      br@y terminal??      Jerson Fernandes      06/16/10 02:31      
         But that's "just" (sic?) another terminal, surely?      Andy Neil      06/16/10 03:25      
      RE: Portmon from Sysinternals      Andy Neil      06/16/10 02:35      
         "pi" cable and two serial ports to log rx and tx      Per Westermark      06/16/10 03:23      
            OK for simple data logging...      Andy Neil      06/16/10 03:27      
               timing etc is just a question of program and OS      Per Westermark      06/16/10 03:56      
            Command-response sync?      Oliver Sedlacek      06/16/10 04:41      
               Don't blame windows here!      Andy Neil      06/16/10 05:14      
                  Don't blame the driver or the adapter      Justin Fontes      06/17/10 14:58      
                     Eh?      Andy Neil      06/17/10 16:42      
                        Huge FIFO because max baudrate also much higher      Per Westermark      06/18/10 02:49      
                  USB-Windows-drivers      Oliver Sedlacek      06/18/10 08:01      
                     Digressing: Multiple USB-to-Serial      Andy Neil      06/18/10 08:24      
                        Digressing Further...      Michael Karas      06/19/10 06:57      
                        Nice      Oliver Sedlacek      06/21/10 02:10      
                           RE: It's a shame I can't tell the service guys what to buy      Andy Neil      06/21/10 02:28      
               8052-based analyser      Andy Neil      06/16/10 05:18      
               Timing just depends on OS and where the data is sampled      Per Westermark      06/16/10 05:38      
      Scripting for development and testing      David Good      06/18/10 10:10      

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