LabVIEW
How does the udp-handshaking protocol in the labview-TCP connect function work?
This is not my experience. How do you monitor the packets? Are you using a packet sniffer (e.g. ethereal)?
Could you attach an example that shows this behavior? What are the destination ports of the UDP packet?
(I can think of several reasons why you might see an UDP packet, but they should not depend directly on the TCP open.
(1) If you specify the target with a hostname, you'll force a DNS lookup (UDP port 53 to your DNS server).
(2) Does your code try a reverse lookup anywhere? (IP--> hostname)? If this fails, (e.g. if you use a private host name that is not listed with the DNS server), the lookup mechanism will probe the target IP directly on port 137/UDP.)
Could you attach an example that shows this behavior? What are the destination ports of the UDP packet?
(I can think of several reasons why you might see an UDP packet, but they should not depend directly on the TCP open.
(1) If you specify the target with a hostname, you'll force a DNS lookup (UDP port 53 to your DNS server).
(2) Does your code try a reverse lookup anywhere? (IP--> hostname)? If this fails, (e.g. if you use a private host name that is not listed with the DNS server), the lookup mechanism will probe the target IP directly on port 137/UDP.)
I don't think that a DHCP request is in any way related to your TCP-open.
(Initial DHCP requests are broadcasts to the generic broadcast address 255.255.255.255, thus any device on the subnet will see it. Unless the receiver is a DHCP server, it will be simply ignored. This cannot have anything to do with your generic errors, because LabVIW will never be aware of this packet).
Your description is not clear enough. Are you seeing the UDP packet incoming on the PC or on the microcontroller (In other words, does it originate on the PC or the microcontroller)? Look at the source MAC address in the ethernet header to make sure where it originates.
How many NICs are on your PC? How do you usually communicate with the microcontroller, is this also via ethernet? Can you ping it? What happens if you try to telnet to the TCP target port, do you get any kind of banner?
Are you sure TCP/IP is configured correctly?
(Initial DHCP requests are broadcasts to the generic broadcast address 255.255.255.255, thus any device on the subnet will see it. Unless the receiver is a DHCP server, it will be simply ignored. This cannot have anything to do with your generic errors, because LabVIW will never be aware of this packet).
Your description is not clear enough. Are you seeing the UDP packet incoming on the PC or on the microcontroller (In other words, does it originate on the PC or the microcontroller)? Look at the source MAC address in the ethernet header to make sure where it originates.
How many NICs are on your PC? How do you usually communicate with the microcontroller, is this also via ethernet? Can you ping it? What happens if you try to telnet to the TCP target port, do you get any kind of banner?
Are you sure TCP/IP is configured correctly?
