Allen-Bradley 1756-CNB User Manual page 101

Action
3. Determine the real scan time of a task.
+
−
C. Look at the scan times.
D. If you want to clear the Max counters and
start over, click Reset.
E. Choose OK.
4. See if the watchdog time is big enough.
Details
Complete these steps while the controller is running.
Controller Primary
Tasks
+
MainTask
Longest time it has taken in
microseconds to scan this task.
Time it took in microseconds to scan this
task the last time it ran.
A. Calculate the smallest watchdog time for your task using the real scan time of the task:
Smallest watchdog time = (2 * maximum_scan_time) + 150 ms
B. Is your watchdog time more than the smallest watchdog time from step 4A above?
• Yes — Stop. Your watchdog time is OK.
• No — Repeat step 2 and enter a new watchdog time.
Configure and Program the Controller
A. Right-click the task and choose Properties.
B. Click Monitor.
Publication 1756-UM523F-EN-P - December 2006
101