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Question When I install NPort Real COM driver, I discovered native COM port performance is faster than NPort, is that normal? And how to improve it?
Question Type Application
Updated 4/1/2008 4:20:41 PM
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Products NPort 5230 Series,NPort Express DE-211,NPort Express DE-311,NPort 5210/NPort 5230/NPort 5232 Series,NPort 5410/NPort 5430/NPort 5450 Series,NPort 5430 Series,NPort 5610/NPort 5630 Series,NPort Server Lite DE-301/302/304/331/332/334


Since NPort belongs to "Serial to Ethernet" device, the Real COM driver and NPort need to work via TCP/IP network, and they will communicate much information to each other during normal operation, such as data communication, setting I/O control, querying line status…and so on. This architecture might take more time during operation compared to native COM ports, especially when the network traffic is very heavy.


  • Win32 PurgeComm() issue

  • Small packets issue

  • Real COM FIFO issue


  • Sometimes user's program might use Win32 PurgeComm() function call which might cause NPorts poorer performance. Select the "Flash Flush" option to improve performance.

  • If data is packed into small packets (write less than 10 bytes) from Ethernet to Serial continually, NPort will take efforts to handle data transparency. Please avoid small packets with NPort’s communication.

  • If your data is always transmitting in small packs from serial to Ethernet, the NPort will take much time for decoding and encoding data and get a poorer performance. You can enable FIFO to improve the performance.

  • Please directly contact " moxa support " by Email.

* Capture logs from " Port Monitor " utility.

If three check points mentioned above are not available for you, I will recommend you capture logs by your manual operation with a freeware named "Port Monitor" . It is a powerful and friendly utility for moxa users, and supports all Windows platforms. If possible, just capture them and forward to "moxa support", it will be helpful for moxa technical engineers to analyze your issue.

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