Help me with a preset time value ?

[KAMEL ELSAYED]

Hello,

I WANT TO MAKE THE PRESET TIME VALUE ( TV ) CHANGEABLE WHEN THE TIMER IS RUNNING .

EXAMPLE : THE START INPUT CHANGES FROM "0" TO "1" AND THE TIMER RUNS FOR THE PRESET TIME FOR EXAMPLE (300 SEC) I WANT TO CHANGE IT TO ANY OTHER VALUE BEFORE IT REACHES ( 0 SEC ).

ALSO I NEED TO KNOW HOW I CAN ENTER AREAL VALUE TO PRESET TIME (TV).

Thanks a lot

 

[daba]

Kamel

The first rule in posting a specific question is to tell us what PLC make and model you are using....

I also suggest you switch CAPS off, it makes it appear that you are SHOUTING.

 

[KAMEL ELSAYED]

hi daba :

the plc is s7 300 cpu 313c and the timer is S_PEXT .
sorry about caps I realized after I finished writing .

 

[daba]

Sorry I can't help with Siemens....

In the Allen-Bradley/Rockwell world you can simply move new values into the .PREset register of a timer, as and when you want to.

I'm sure experienced Siemens guys will step in (pun intended)....

 

[KAMEL ELSAYED]

thanks daba

i am waiting for Siemens guys reply

 

[MaReKA]

I have to admit that I have no field experience with Siemens programming yet (a decade of A-B, and everytime I use Step7 or TIA I want to add another..), but based on what I've learned in school what you want needs further programming...

Timer presets are typically stored as S5Time data types, without additional logic you are not able to use a real value as a preset for a timer. Basically the data type stores a BCD preset value of 0-999 together with a time base of 10ms up to 10s. It may be easy to convert a REAL value of a given time base but it will get more complex if you have to calculate the time base for any given REAL value (e.g. A value ranging from 0.01s to 60s).

S5Time Data Type:
https://support.industry.siemens.com/cs/document/56243/storing-the-s5time-data-type?dti=0&lc=en-WW

A quick search brought up this thread about converting REAL values for use as a preset:
https://support.industry.siemens.co...e-changed-from-wincc/54165?page=0&pageSize=10

As the timer functions count down from TW there is no easy way to apply a new preset while the timer is active, you will have to restart the timer to apply the new preset.
You can possibly calculate an intermediate preset time based on the actual time left and the new preset on change of the preset...

 

[Lare]

It is easeier if you avoid old S5 timer types. Use SFB3, SFB4 and SFB5 IEC timers instead (TP, TON, TOF), they work like in other PLC's (input/output = time, mseconds on dint format / t#1s )

 

[KAMEL ELSAYED]

thanks mareka and lare,

reply to mareka,
i opened links it is very useful
i will take my time to try every thing on it
actually i made the calculation for preset time value , to calculate it i changed it from s5time to real type after i got the result i can not move it to the preset ( tv ) because it is not s5time type .

reply to lare ,
i am trying SFB3, SFB4 and SFB5
i will get you the result after i finish

 

[adfox]

As I recall correctly SFB3/4/5 are using TIME format. So basically its DINT in miliseconds.

 

[KAMEL ELSAYED]

thanks adfox,

i am trying with sfb5 but i can not adress it yet.
also i want to say that i am still learning and it is the first project for me

 

[KAMEL ELSAYED]

hi all,

sfb5 and fc40 did not work with me i put a format time type on (pt,in) and the tow gives me system fault

pleas help me

 

[adfox]

This timer is preset with 5s (5000 ms).
http://imgur.com/a/xpmSO

 

[KAMEL ELSAYED]

Yes adfox,

I entered (t#30000ms) on (pt) and i got system fault
i think that the problem with the plcsim

 

[Lare]

What diagnostic buffer says?
Have you loaded all blocks to PLC?
Db-block missing from CPU?

 

[KAMEL ELSAYED]

hi lare,

i think that i loaded ob1_block only
should i load db_block also ?