Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 165)

Publication 1760-UM001D-EN-P - September 2005
Retention 7-15
Operating Hours Counter for Maintenance Intervals
Task 2
Every 1000 hours, the system or machine must undergo preventive
maintenance. Filters and transmission oil must be changed and the
bearings must be lubricated.
Contacts and relays used:
Function of the Pico circuit diagram:
T8 provides the clock pulse. When a time of t = 30 minutes is
selected, the counting period amounts to 2 x t = 60 min. Every hour,
one pulse is counted. The up counter C8 triggers a warning light at
1000 by means of Q4.
For the clock pulse to be correct when there is a power outage, T8
must be retentive.
M16 prevents C8 from accidentally receiving a counter pulse when the
power is turned back on if there was a power outage during the
counting period.
Both M16 and C8 must retain their actual values at power outage so
that the 1000 hours of operating with interruptions in the power
supply can be counted.
I1 (for example, a key-operated switch) is used to reset the counter.
Coil Function
T8 Clock pulse
M16 Block double pulse
Q4 Warning light, 1000 h reached
C8 Up counter
I1 Reset
-----------TT8
T8-M16-----CC8
-------SM16
T8--------RM16
C8---------{Q4
I1---------RC8
RT8
18:38
30.00
TRG
RES
T8
+ {
{
M:S
1000
DIR
CNT
RES
C8
+
0107
{
{
Circuit Diagram: Parameters entered: