User manual

Toolbox 32 User Manual 1.47d www.cse-semaphore.com/mykingfisher
Page
68
Ladder Logic - Timer
The following parameters are used by each Timer block:
Timer Register: (#T1 to #T64) Each timer register can only be used once in ladder logic. Note: for standard
time intervals (eg. 1 second, 1 minute, 1 hour), it is recommended that Timer Flags (eg. #YTICK.SEC ) be
used instead of a Periodic Timer block. Unlike Timer registers, Timer Flags can be used multiple times in
ladder logic.
Period: (Constant or #R). Specifying a local register allows the period to be changed while the ladder is
running.
Units: 100ths (of a second), Seconds, Minutes, Hours, Days, Weeks, Months or Years.
Timer Accuracy: One Unit (as configured above). Eg a 10 minute timer will have an accuracy of 1 minute.
While a 600 second timer (also 10 minutes) will have an accuracy of 1 second. Timers use the real-time
clock to determine when to increment. When the specified time unit changes in the real-time clock, the timer
increments. This means that if a timer is started using an ON-DELAY or an OFF-DELAY block, the timer
could increment very soon or up to 1 time unit later depending on when the timer units in the real-time clock
change.
On-Delay Timer
An on-delay timer is always used with one or more contacts. The on-delay timer becomes true when the
contacts on its left-hand side are true and have stayed true for at least the specified time period. When the
left-hand side contacts become false, the on-delay contact becomes false also. Eg. the on-delay contact will
become true when bit 1 of R1 is ON for 5 seconds and will remain true while bit 1 remains ON. As used in
the topic Example - Exception Reporting Digitals.
Off-Delay Timer
An off-delay timer is always used with one or more contacts. The off-delay timer will keep the left-hand side
of the rung true for the specified time period after the left-hand side of the rung becomes false. Eg. the off-
delay contact will stay true (and cause the rung to remain true) for 5 seconds after bit 1 of R1 becomes false.
Periodic Timer
A periodic timer requires 3 parameters - a timer register (#Txx), the time period (0-32767) and the time units
(100ths [of a second], seconds, minutes, hours, days, weeks, months, years). This contact becomes true for
one ladder scan every time period. As used in the topic Example - Timer Flag. Note: if 100ths is used for the
time units and the I/O Scan Interval is greater than 10 ms (ie. the ladder is scanned less than 100 times per
second), the accuracy of the periodic timer will be affected.