Mitsubishi PLC's timing expansion programming - Database & Sql Blog Articles

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The maximum timing of the Mitsubishi plc timer is 3276.7s. If longer timing is required, the circuit shown in Figure 1 can be used. When X2 is OFF, T0 and C0 are in reset state and they cannot work. When X2 is ON, its normally open contact is turned on, T0 starts timing, and the timer time of 100ms timer T0 after 3000s is reached, its current value is equal to the set value, its normally closed contact is disconnected, and it resets itself. After reset, the current value of T0 becomes 0, and its normally closed contact is turned on, causing its own coil to be "energized" again and timing begins. T0 will work in this way until X2 becomes OFF. From the above analysis, the top line of the circuit in Figure 1 is a pulse signal generator with a pulse period equal to the set value of T0.

The generated pulse train is sent to the C0 count. After counting 30,000 (ie, 25000h), the current value of C0 is equal to the set value, and its normally open contact is closed. Let T0 and C0 be set to KT and KC respectively. For 100ms timer, the total timing is

T=0.1KTKc(s)

For example, the clock with a period of 1 min is supplied to the counter with the contact of the special auxiliary relay M8014, and the maximum fixed time of the single timer is 32767 min.