User Manual

106
Using the Simple Program Function Section 4-15
Starting Method Any of the following three methods can be used to start the simple program.
• Setting the “program start” parameter to STRT.
• Turning ON an event input. (The program start must be assigned to an
event input. See note.)
• Starting with an Operation Command using communications. (When the
program start is not assigned to an event input.)
Note When an event input is used to start and reset the simple program, writing is
performed to EEPROM. Be sure to consider the write life (1 million writes) of
the EEPROM in the system design. When the program start is assigned to an
event input, the “program start” parameter will function as a monitor display,
and the RSET/STRT displays can be used to check when the event input has
started or reset the simple program. When this is done, the “program start”
parameter functions as a monitor display only and cannot be changed using
key operations. If the “program pattern” parameter is set to OFF, the event
input assignment setting will be initialized to “none.”
Soak Time and Wait Band
The wait band is the fixed band within which the process value is stable in
respect to the set point. The soak time is measured within the wait band. The
timer that measures the soak time operates only when the process value is
within the wait band around the set point (i.e., SP
± wait band). In the following
diagram, the timer will be stopped between the start and (1), (2) and (3), and
(4) and (5) and will measure the time only between (1) and (2), (3) and (4),
and (5) and the end.
Note If the wait band is set to OFF, the wait band will be treated as infinity and the
timer will measure time continuously after changing from RSET to STRT.
RSET → STRT
PV
(5)
(1) (2) (3)
(4)
Set point
Wait band
Wait band
Soak time
remain
Set
p
oint Set
p
oint