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The "TON" Timer
- From the Main Menu of the
PSIM program, select the I/O simulation display.
- Toggle Function Key [F2]
until the minimum I/O Data Table is displayed in the
upper box of the display, and the Timer Table is
displayed in the lower box of the Data table display.
- Select the Rung Editor [F5]
and enter the following ladder Logic program.
- Once you have entered your
program, select the Program Utility menu and save your
program to disk. Now exit the Rung Editor and return to
the I/O simulation Display.
- Note the initial value of
timer T1's accumulator, preset and the state of both its
done and enable bits.
T1:A = ___________ T1:P =
____________ T1/DN = ____ T1/EN = ____
- Close switch I:0/00 and
observe the incrementing of T1's accumulator and the
setting of its Enable and Done bits.
- Note the final value of timer
T1's accumulator, preset and the state of both its done
and enable bits.
T1:A = ___________ T1:P =
____________ T1/DN = ____ T1/EN = ____
- Toggle the state of switch
I:0/00 a number of times and observe the operation of the
Timer.
Cascaded Timers
- Ensure that switch I:0/00 is
open; then Select [F5] the Rung Editor and modify your
program so that it matches the following:
- Once you have completed your
program, save it to disk and return to the I/O simulation
display. Toggle the state of switch I:0/00 to ON and
observe the operation of the timers in your program.
- Pay particular attention to
the way in which the timers are cascaded. (Timer #2 is
enabled via the done bit of Timer #1).
Self Resetting Timers
- Ensure that switch I:0/00 is
open; then Select (F5) the Rung Editor and modify your
program so that it matches the following. (XIO T:2/DN
instruction on Rung 1)
- Once you have modified your
program, save it to disk and return to the I/O simulation
display.
- Toggle the state of switch
I:0/00 to ON and observe how the timers are now fully
cascading in their operation.
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