The timer is most commonly used PLC instruction. Timers set the output to 1 at specific time intervals which is called preset time. when input of timer condition is true than timer start running until preset value reached. When timer actual value is equal to preset value than timer stopped and set timer output to 1. The following four types of timer are available in Mitsubishi. Address of timer start with the device number, and the preset.Output coil represent the timer in a program

• Low-speed timer : Counts time in increments of 100 ms.
• High-speed timer: Counts time in increments of 10 ms.
• Low-speed retentive timer : Accumulates time in increments of 100ms.
• High-speed retentive timer : Accumulates time in increments of 10ms

The timer present values during step run are as follows.
• 10 ms timer Incremented by one each scan.
• 100 ms timer, 100 ms retentive timer Incremented by one every ten scans.

range of the timer

The allowable range is unsigned int type(USINT) so you can set your timer k1 to k32767.

range of the time

for maximum to minimum value of time for Low-speed (100 ms) timer 0.1 to 3276.7 s and for high speed timer 0.01 to 327.67 s .

total no of timer

Maximum to minimum timer no T0 to T2048.

parameter of timer instruction

• Timer number - timer no is identification number of your timer you can declare your timer like T0 , T1 up to T2047(2048).
• preset time - preset time is duration of the timer. Preset indicates unit of time base.for example a low speed timer having timer number T0 with and preset value of K30. so timer timer run 30 x 0.1 Sec = 3 sec. so your timer run only 3 second not 30 second.
• Preset timers are integer value so you can define your timer preset value 1 to 32767.you can define your timer by device K or D.
• if you want to change your value by OPC, HMI, SCADA so always use Device 'D'.

timer setting

if you want to change timer base or timer limit setting

• open the Project Data List
• double-click on Parameters
• double-click on PLC Parameters
• click on the PLC system tab

low speed timer

Low-speed timer, Counts time in increments of 100 Ms. Output coil represent the timer in a program so for declaration of timer insert a coil and declare timer no and preset value (T0 K50) separated by a space and press ok for example T0 K50 where T0 timer number and K50 is preset value of timer . insert a output coil and addressing of low speed timer : timer address, and preset separated by a space for example "T1 k50"

where T3 is tmer number and K50 is timer preset value.

in low speed timer base is 100ms so if your preset value is k50 than timer runs only 5 second. 50 x 100ms = 5 sec similarly if preset value is k100 than your actual timer running period is 100 X 100ms = 10 sec.

in this example T0 timer number and K50 is timer preset value. in next rung timer address is used as 'NO' contact. if input of X0 is true than timer start for defined preset value, when timer actual value is equal to preset value than output of timer set to true otherwise false.

high speed timer

high-speed timer, Counts time in increments of 10 ms. To address a high speed timer use a output coil instruction , H Timer address and preset value separated by a space. insert a output coil and addressing high speed timer : H, timer address, and preset separated by a space for example "H T1 k50"

where
• H : high speed timer.
• T5 is timer number.
• K50 timer preset value.

in this example T1 is timer number and K50 is timer preset value. in next rung timer address is used as 'NO' contact. if input of X1 is true than timer start for defined preset value, when timer actual value is equal to preset value than output of timer set to true otherwise false.

retentive timer

when the input of retentive timer is set to true retentive timer starts increasing. when current value is equal to the preset value, a retentive timer goes time out and its contact turns on. If the input condition of retentive timer is turned off during that increment (timer run), the coil is de-energized but the current value is kept. To restart the increase, which means to accumulate values, turn input conditions on again to re-energize the coil.

declaration of retentive timer in plc

To use retentive timers, it is necessary to declare them in the PLC parameters:
• open the Project Data List
• double-click on Parameters
• double-click on PLC Parameters
• click on the Device tab
• This will open the following dialog box. Enter the number of retentive timers Click on the End button when done.

Low-speed retentive timer

insert a output coil and address a Low-speed retentive timer: Retentive timer address and preset separated by a space for example "ST1 k50".

• ST1 is retentive timer number.
• K30 timer preset value.

high speed retentive timer

high speed retentive timer is same as low speed retentive timer except base. high speed retentive timer Accumulates time in increments of 10ms.

• h indicate high speed timer
• ST1 is retentive timer number.
• K50 timer preset value.

---

how to reset Retentive timer

The accumulated value of a timer returns to 0 when the input conditions of the timer rung become false. This is not the case with retentive timers. To return a retentive timer accumulated value to 0 it is necessary to use the RST T# instruction. Retentive and non-retentive timers will lose their accumulated values at power down unless they have been declared battery-backed in PLC parameters. An RTS instruction must be used to turn off the contact and clear the current value after the retentive timer goes time out.

if the X4 is set to true low speed and high speed Retentive timer is reset accumulated value.

---

how to set timer preset value externally

if you want to change your value by OPC, HMI, SCADA or externally so always use Device D. following example shows how to set timer value externally

if input X5 is set to true value of D0 move to D1 and the D1 is a preset value of timer so it set the preset value of timer.