YASKAWA MP920 User Manual page 162

7 218IF Module
7.5.5 Transmission Parameter Settings
INFO
TERMS
4. Count of Retry (Number of Retries)
Enter the number of retries (0 to 255) to be attempted when a timeout is detected for a
system function (the MSG-SND function). An error will be returned for the MSG-SND
function if a response is not returned after the set number of retries.
The Count of Retry parameter is not required if only the TCP protocol is used. Set parameters 3 and 4
to 0.
CP-218 Connection Parameters (Connection Parameter Settings)
5. CNO (Connection Number)
Shows the connection number (1 to 20).
When communications are performed using an Ethernet Module, the remote stations are
identified by a connection number in the range from 1 to 20.
This CNO corresponds to "Remote Connection #" (parameter 02) of the MSG-SND and
MSG-RCV system functions.
6. My Port (Local Station's Port Number)
Enter the local station's port number (256 to 65,534) for each connection. Be sure to
enter a port number that is not used for another connection or for diagnostics. If 0 is
entered for this parameter, the data for that connection number will be cleared and
"- - - -" will be displayed in the My Port column.
7. DST. IP Address (Remote Station's IP Address)
Enter the remote station's IP address for each connection.
The range of data to be entered differs for each field of the DST. IP Address.
• Field No. 1: 0 to 255 (except 127)
• Field No. 2: 0 to 255
• Field No. 3: 0 to 255
• Field No. 4: 1 to 254
For the impassive open mode, enter 0 in all four fields.
Connection
A "connection" involves a series of operations used to perform reciprocal transmission checks and
data transfer so that one-to-one communications can be performed between local station programs and
remote station programs. With connection protocols, there are procedures such as arrival checks, error
detection and actions, sequence number checks, and controls on the amount of transmission data, thus
ensuring highly reliable communications. With non-connection protocols, there are no procedures for
guaranteeing the quality of communications, and data is transmitted in one direction only. Unlike con-
nection protocols, there are no complicated procedures, and processing is simple, thus enabling high-
speed communications, but the reliability of communications is reduced. TCP is a connection proto-
col, and UDP is a non-connection protocol. In general, TCP should be selected when the reliability of
communications is important, and UDP should be selected when the speed of communications is
important.
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