EET 277 Lab 7 and 8; RSLogix Timers and Counters
Name: ___________________________
Part 1) Timers:
1) What type of PLC are you using? ____________________
What time bases are available you to with this processor? _______________________
2) What is the shortest (but not 0) and longest Preset time (Time base x Preset) of a timer
available to you?
Shortest=_________________ Longest? _________________
Provide the addresses for the three binary Control Bits, and two words of this instruction For Timer T4:0.
Address
Description
The number of time base units a timer will count to
The number of Time Base units the timer has already counted
The bit to indicate that the timer is activated
The bit to indicate the timer is incrementing
The bit to indicate that the timer is finished incrementing
3) What is the Default Timer File of a SLC 500 or MicroLogix processor? _________
4) How many timers will an SLC 500 or MicroLogix 1200 or 1500 allow in the default Timer File?
5) Can a timer have a negative Preset? ___________ a negative accumulated count?___________
6) Can an RTO be reset without using a Reset Command? (If so explain how)
7) A timing TON with a Preset of 30S has an accumulated time of 5 seconds when the Accumulator is changed
to 20S. After the change how long will it take for the timer to time-out?
8) What will happen if the Accumulator of a timing-timer is set to a number greater than the Preset value?
9) What will happen if the Accumulator of a timing-timer is set to a negative number using the Timer Data
File? What must be done to resume running the program?
10) Can any SLC 500 or MicroLogix Timer in any Timer File be designated “Retentive” or must all, or only
certain ones, be retentive?
EET 277 Lab 7 and 8; RSLogix Timers and Counters
11) When will the counter increment?
12) Program a ladder diagram including each of the
timers available (TON, TOF and RTO) and show
when the Timer-Timing and Done bits will be on if the Presets are 3seconds.
13) Program the PLC to turn on Output 0 for 1.5 seconds, then off for 2.5 seconds while Input 0 is on. If Input
0 is off, Output 0 should be off, but as soon as Input 0 is turned on, Output 0 should turn on for 1.5 Seconds
then continue to cycle.
Use Symbols and Rung Comments to explain what each part of the program does.
EET 277 Lab 7 and 8; RSLogix Timers and Counters
14) When Input 1 is on, have outputs 1, 2, and 3 cycle as follows. All outputs should be off while Input 1 is off.
When input 1 is turned on, turn on output 1 for one second then output 2 for one second, then output 3 for one
second. 2 then all off for one second, then continue to cycle. If I/1 is turned off at any time, turn off all of the
outputs. Call the times between transitions t1-t4 where t4 is the time when all of the outputs are off before
restarting.
15) Add rungs to the program to allow the value stored in N7:2 to change the timer
presets. To do this you will need to use Move instructions to move the value into the
Presets. If you have 4 timers you will need 4 move instructions.
Demonstrate you program to your Instructor: ____________________
Part 2: Counters:
1) How many counters will an SLC 500 or MicroLogix 1200/1500 allow in each Counter File?_____________
2) What are the limits of the Accumulated Count?___________ to ________________
3) Provide the addresses for the bits and word used to monitor and control Counter C10:5.
Address
Description
The number of false to true transitions a counter is to look for
The number of false to true transitions the counter has already counted
When this bit goes from false to true the counter will increment once
When this bit goes from false to true the counter will decrement once
The bit to indicate that the Accumulated count ≥ Preset
The bit to indicate the counter incremented beyond its numeric limits
The bit to indicate the counter decrement beyond its numeric limits
II) Enter the following Program: and use it to determine the output states indicated.
EET 277 Lab 7 and 8; RSLogix Timers and Counters
4) In the program above why do both the CTU and CTD commands control C5:0? Could the CTU and CTD
Preset value be different? Why?
5) When does the counter actually count? On the False to true Transition (Rising Edge) or True to False
(Falling Edge)
6) Can the Counter Count-down while the Count-up is enabled? Why?
7) When is the Done bit set? Explain in terms of the Preset and Accumulator?
9) Set the Accumulated Count to 32767 then close CNT_UP once. The Accumulated Count should be -32768.
Why is the Done Bit still on?
10) In the Counter Data File, reset the “OV” bit. What Happens to the Done Bit? Why?
11) With the Accumulated Count at -32768 and all Control Bits off, Close CNT_DN to cause the counter to
count down one time. The Accumulated Count should be +32767. In the Counter Data File Counter Control
Word, what bit is set?
Part 2 Clock: (Cascading Counter)
1) Using a 1-second self-resetting timer and 4 counters, make a clock that will track days, hours, minutes and
seconds. Use a 7 day week and if Sunday is Day 0, set the correct time.
Demonstrate you program to your Instructor: ____________________