Siemens Step 7 SFB 4 "TON"

[vanilla05]

Dear all,

i tried to use the SFB 4 timer but it seems that the timer just refused to count and im not sure why.

I understand that with an IN and time at PT, the output bit will be activated when PT finish timing. But what happen was that the output bit becomes 1 as soon as the IN becomes 1.

Basically, there isn't any delay.

Will anyone kindly attached a print screen on the variables and Db linked to SFB 4?

 

[alanderson]

I attached a call to SFB4, DB4 (instance DB), and DB3.

I tried it 2 different ways and it worked.

 

[L D[AR2P#0.0]]

If running in the simulator, have a look here:

http://www.plctalk.net/qanda/showthread.php?t=37212&highlight=sfb4+simulator

 

[alanderson]

I didn't think about sim.
Just another reason why I like a real PLC on my desk.

 

[vanilla05]

Hi alan and L D[AR2,P#0.0],

thanks for your prompt reply. the problem indeed lies in the simulator. The problem is solved as soon as i installed the patch. Thank you once again.