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Question I can PING & Telnet NPort. Why can not my own UDP program Rx/Tx data via NPort properly?
Question Type Application
Updated 4/1/2008 4:09:47 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,NE-4100T,NE-4110S,NE-4110A,NE-4120S,NE-4120A,NPort Server Lite DE-301/302/304/331/332/334,NPort DE-311M



1. Improper operation mode.

2. NPort's UDP port is not correct.

3. DHCP issue.

4. Improper [Desti. IP] setting.

5. Firewall filtering rules.

6. Improper DIP switch settings on DE-311/211.

7. Data loss.


  • Your operation mode must be [UDP mode].
  • The NPort's UDP Port must match your own UDP program.
  • If your Host and NPort are in a DHCP environment :
    a) You have to assign a fixed IP address to NPort & your Host.
    b) In a DHCP environment, you can map a specific IP address to your NPort's & Host's MAC address.
  • Your [Desti.IP] must be the same as your host’s current IP.
  • Make sure that your firewall can open the TCP port.
  • The DE-311/211's DIP SW1 must be OFF for data communication.
  • Initially, UDP can NOT guarantee data won’t be lost. But we still can do something for this problem. That is,
    a) Purify your network traffic as best as you can.
    b) Your program should be able to handle a resending mechanism when the data is lost.
    c) Change to use TCP Server / Client architecture.

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