Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 391)

Application Example Programs
E–41
Adjustable Timer Application Example
The following application example illustrates the use of timers to adjust the drill
dwell time at the end of the machines downstroke. For a detailed explanation of:
•
XIC, TON, and OSR instructions, see chapter 6.
•
LES and GRT instructions, see chapter 7.
•
ADD and SUB instructions, see chapter 8.
Valid dwell times are 5.0 seconds to 120.0 seconds. Adjustments are made in 2.5
second intervals.
Each time I/8 or I/9 is depressed, the timer preset or delay is adjusted up or down
accordingly. By altering the value of N7:0 the amount of change can be increased
or decreased. The constants in the LES and GRT instructions, and in the source and
destination of the ADD and SUB instructions, could be changed easily to integers
for even greater flexibility.
Adjustable Timer Ladder Program
Rung 2:0
Adds 2.5 seconds to Timer delay each time the increment push button is
depressed. Do not exceed 120.0 seconds delay. Note that N7:0=250.
| Increment |
| Timer preset |
| I:0 +LES–––––––––––––––+ B3 +ADD–––––––––––––––+ |
|––] [––––––+LESS THAN +––––––[OSR]–––+ADD +––––|
| 8 |Source A T4:0.PRE| 0 |Source A T4:0.PRE| |
| | 500| | 500| |
| |Source B 11750| |Source B N7:0| |
| | | | 0| |
| +––––––––––––––––––+ |Dest T4:0.PRE| |
| | 500| |
| +––––––––––––––––––+ |
Reference