Communication
FPΣ User's Manual
242
8.7.7.1 Reducing Transmission Cycle Times
If there are stations that have not been added to the link, the link addition processing time
(Tlk) and with this the transmission cycle time will be longer.
T max. = Ts1 + Ts2 + • • • • • • • + Tsn + Tlt + Tso + Tlk
Tlk = Tlc + Twt + Tls + Tso
Tlk= link addition processing time
Tlc = link addition command sending time
Twt = addition waiting time
Tls = link error stop command sending time
Tso = master station scan time
With the SYS1 instruction, the link addition waiting time (Twt) in the above formula can be
reduced. Thus, SYS1 can be used to minimize the increase in the transmission cycle time.
EXAMPLE
Set SYS1 to change the waiting time for a link to be added to the PLC link from the
default value of 400ms to 100ms.
LD Body
NOTE
• If there are any stations that have not been added to the link, the setting
should not be changed as long as a longer link transmission cycle time
does not cause any problems.
• The SYS1 instruction should be executed at the beginning of the program,
at the rise of R9014. The same waiting time should be set for all linked
PLCs.
• The waiting time should be set to a value of at least twice the maximum
scan time for any of the PLCs connected to the link.
• If a short waiting time has been set, there may be PLCs that cannot be
added to the link even if their power supply is on. (The shortest time that
can be set is 10ms.)
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