Sharp Z-336J - Manual (Page 168)

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Chapter 15: Appendix
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[5] FL-net sub net mask
The sub net mask on an FL-net is always "255.255.255.0." The user does not need to set this sub net
value.
This value is identical to the original network address section and the device address section of the
class C.
[6] TCP/IP, UDP/IP protocols
TCP, UDP, and IP are major protocols used on Ethernet networks.
The IP is located in the network layer of communication protocols and controls the flow of communica-
tion data.
The TCP and UDP are located in the transport layer. Both use the IP as a network layer. However, there
is not much difference between these protocols in their details.
The TCP provides reliable service that does not care about the partition of data in the upper layer. On
the other hand, the UDP transfers groups of data (data diagram) from the IP to the upper layer without
any modification. It pays no attention to whether or not the data arrives nor does it care what the
destination is. Confirmation of the data being received and re-sending the data is the job of the upper
layer.
Although the UDP is not reliable, compared with the TCP, its advantage is that it has a small communi-
cation overhead.
The FL-net uses the UDP. This is because the TCP's data confirmation and re-sending procedures
make it difficult to meet the FL-net goals. By omitting this procedure, the FL-net protocol layer controls
data transmission correctly using tokens. And it divides and recombines multiple frames, so that it can
provide high speed data exchange.
[7] FL-net port number
In order to offer service from the FL-net protocol layer, that is the upper position of the transport layer,
the following port numbers are already specified. However, the user does not need to set the param-
eters for these port numbers.
FL-net port number
Name Port number
1 Port number for cyclic transfer 55000 (fixed)
2 Port number for message communication 55001 (fixed)
3 Port number for a participation request frame 55002 (fixed)
4 Port number for sending data 55003 (fixed)