21/01/2026
⏱️ Timers for Minutes & Hours in Process Automation
In process automation, we often need PLC timers to count minutes or even hours
(for soaking time, delays, batching, heating, drying, etc.).
However, some PLCs have timer limitations:
Mitsubishi & Xinje PLCs → maximum timer base 100 ms
Haiwell PLCs → maximum timer base 1 second
So we cannot directly set long time values using a single timer.
✅ Practical and reliable solution
Use a 1-second timer together with a data register.
Logic concept:
Run a 1-second timer
When the timer is DONE, ADD 1 to a data register (time counter)
Reset the same timer
Repeat the cycle to build minutes / hours
This approach is:
Simple and stable
Easy to understand
Easy to troubleshoot
Applicable to many PLC brands
📌 Sample ladder program is attached,
implemented using Haiwell PLC (Happy software) to demonstrate the concept clearly.
