Mitsubishi Melsec-L Series User Manual page 251

• When a communication failure occurs due to a problem such as noise, change the value so that the number
of retries may increase. The number of retries is obtained using the following formula. (When using the
default values, 2 = (60  20) - 1)
Number of
When the number of retries is two and data sending fails, a data sending error occurs at the timing shown
Ex.
in the figure below (in communications using the fixed buffer).
BUFSND instruction
BUFSND instruction
Completion device + 1
Data
command
A: TCP resend timer value
(The time at which data are sent when ACK is not returned after data transmission)
• When not performing the above retry process (set 0 times), configure the setting so that the following
formula is met.
(Set the same value for the timer values.)
TCP ULP timer value
=
retries
TCP resend timer value
E71
1st retry
A A
TCP ULP timeout value
TCP ULP TCP end
= =
timer value timer value
- 1
2nd retry
A
TCP resend
timer value
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