Timer Preset min & max value

[Kikis]

Hi Guys,

 

I was thinking that it will be very useful to have min and max value limit entries option for the timer Preset entry for Vision series.

 

In the following star-delta motor starting example, i use T1 as a delay in order to make sure that star contactor will be de-energised before delta contactor is energized.

Even though i use electrical interlock circuitry to prevent short-circuit, i always prefer to provide also an electronic safety. 

Since response time of the PLC outputs is much faster than the response time of the contactor coils, T1 delay is required.

 

Today i had a call from one of my customers saying that there is something wrong with the motor of his air pressure booster which is controlled by a V130. The problem was that someone changed T1 preset value from 00:10 to 10:00 by mistake (10sec instead of 100mS).

 

Just a practical example of a problem in the real world!

[Flex727]

Use "Legal Entry" in the HMI input to know when the timer has been updated. Then compare the Timer Preset with the min and max values you want. You can either reset the preset to the min or max value, or pop up a screen that informs the operator that they've made an error.

 

The option you suggest does exist for numeric entries and I agree that it would be nice to have it for Timer inputs also.

[V700]

Same problem here.
Flex727  can you explain it in more detail please?

Thank you.

[Flex727]

Assign an MB to the field for Legal Entry. When that bit goes high, an entry was made to that variable. You can then test that entry in ladder in any way you need.

[V700]

Thanks for reply!

 I want time to be >=00:00:05

How can i put the timer value that the user gave in input A ?

 

 

 

[Flex727]

Under the Store menu, use Load Timer/Counter Preset. You'll probably want to use an ML as the units are in 10ms (the value for 5 sec would be 500).

[V700]

Thank you!