Types of Timers in Programmable Logic controllers

Mitsubishi PLC timer type

The timer in the PLC is a device inside the PLC. Its function is equivalent to the time relay in the relay system. There are several hundred timers inside. The timer is based on the accumulated timing of the clock pulse. There are three kinds of clock pulses: 1ms, 10ms, and 100ms. When the measured time reaches the set value, the output contact operates.

The integrated timer has the function of counting accumulation. If the power is turned off or the timer coil is OFF during the timing, the calculation is calculated.

The current device will maintain the current count value (current value), and continue to accumulate after power-on or the timer coil is ON, that is, its current value has a hold function, and the current value becomes 0 only when the integrated timer is reset.

(1) The 1ms integration timer (T246 to T249) is a total of 4 points, which is the cumulative counting of 1ms clock pulses. The timing time range is 0.001 to 32.767s.

(2) The 100ms integration timer (T250 to T255) has a total of 6 points, and the time range for accumulating the count of 100 ms clock pulses is 0.1 to 3276.7 s.

The general-purpose timer is characterized by the fact that it does not have a power-down hold function, that is, the timer is reset when the input circuit is disconnected or powered off. The general-purpose timer has two types of 100ms and 10ms general-purpose timers.

(1) 100ms general-purpose timer (T0~T199) A total of 200 points, of which T192~T199 are sub-programs and interrupt service program-specific timers. This type of timer is a cumulative count of 100ms clock, the set value is 1 ~ 32767, so its timing range is 0.1 ~ 3276.7s.

(2) A total of 46 points for the 10ms general-purpose timer (T200 to T245). This type of timer is a cumulative count of 10ms clock, the set value is 1 ~ 32767, so the timing range is 0.01 ~ 327.67s.

The selection of the timer setting value.

During programming, the timing constant must be set after the timing logic coil that determines the timer unit is using the output OUT command. The timing setting value can be determined directly by the constant K (usually using the decimal number K, K range 0~32767), or can specify an address number with the power failure holding data register D, the number stored in the data register D K (general

Use the decimal number K, the range of K -32768~32767) as its set value.

The timing unit of the timer TO of the Mitsubishi FX2 PLC is 100ms. If the set value is directly constant K, K is set to 100, that is, the timing time T=10S. The timing unit of the timer T35 of the Mitsubishi FX1S PLC is 10 ms. If the set value is stored in the 16-bit power-down hold data register D of the address number 250, and its value K is 50, the timing time T = 0.5S.

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