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4.4

UDP

UDP (User Datagram Protocol) is a Datagram Communication Protocol and doesn’t guarantee

the stability in Transport Layer above the IP Layer. It also provides Communication between

Applications using Port Numbers. UDP can communicate with more than one Peer and doesn’t

require the Connection Process. On the other hand, UDP has Data Loss and receives Data from

any Peers because UDP has no guarantee reliability. UDP Transmission Methods are Unicast,

Broadcast and Multicast according to Data transmit/receive range.

Figure 8 shows UDP Operation Flow.

Figure 8 UDP Operation Flow

4.4.1 UDP Unicast

UDP Unicast is the first Communication Method in which sender is one and receiver is one.

Before Data Transmit, SOCKET performs the ARP Process. In the ARP Process, if there is no

response from Peer against of ARP Request within the Retransmission Time, Sn_IR [TIMEOUT] is

set to ‘1’. (Ref 4.8.1 ARP & PING Retransmission)

If previous Destination and current Destination are the same, the ARP Process is skipped.

Also, the ARP Process is skipped by Sn_CR [SEND_MAD] and Sn_DHAR.

 OPEN

SOCKET n is configured as UDP Mode by OPEN Command.

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