Siemens S7 having trouble with using timers in FB's

Derman0524

Member
Join Date
Dec 2018
Location
Toronto
Posts
22
So long story short I'm frustrated at work because I can't get my timer to actually time in the FB's. I have been using the SB4 blocks in my FB with instance DB's and using STAT for the name of the block.

I'm extremely new to Siemens but I want to get good at it but this has been really annoying. When I go online with the PLC and output a 1 to EN of the timer, it instantly displays a 1 at ENO, the timing never works even when putting a T#3s value at PT.

Any help would be greatly appreciated, thanks!
 
So I ditched the SBF4 and I'm using a standard FB1 call from OB1. A normal on delay timer works in FB1 now but when I energize FB1 in OB1 with the starter input, the two outputs energize instantly without delay from FB1.

How does FB1 get delayed in OB1? If i run FB1, the coils properly get delayed but I just want the two outputs in OB1 to get delayed at the same time as FB1.

Photos attached

Siemens Help 1.png Siemens Help 2.png
 
So I added a 3rd rung and a return coil. Does the return coil return the boolean value at the FB1 block in OB1? That seemed to have made it work as I wanted too.

Siemens Help 3.png
 
So I ditched the SBF4 and I'm using a standard FB1 call from OB1. A normal on delay timer works in FB1 now but when I energize FB1 in OB1 with the starter input, the two outputs energize instantly without delay from FB1.

How does FB1 get delayed in OB1? If i run FB1, the coils properly get delayed but I just want the two outputs in OB1 to get delayed at the same time as FB1.

Photos attached

You probably want to try switching back to the IEC style timer, instead of the S5 timers (T4). The S5 timers are mostly there for backwards compatibility, and IEC style is recommended for most new applications.

The older style technically work, but if you have to call your FB more than once, things get complicated quickly.
 
Can you post a photo example using the IEC style timer please? i ditched it because I was having troubles with it. A simple 1 or 2 network example will suffice.
 
I'm not sure if I'm just stupid but I got it to work with the IEC timer. I think I was just over thinking it and confusing myself but I got it to work and I understand how it works now, for the most part. Really appreciate the help!
 
You can find the IEC timers in the standard library, under system function blocks, SFB4 would be one as shown in P#'s post.


ENO is pretty much the same as EN, so whenever a block is called, the ENO is active.


In your FB, you want to write to your FB output, on the outside of the FB you will add the outputs to these pins.
 
Example use of on delay IEC timers. Start must be on for 2 secs before motor starts. Once started, motor runs for 10secs then stops.

str.jpg
 
You don't have to be a ******** about it. We're all here to learn

My apologies if my comment looked rather harsh. When I was typing my reply your comment about getting it to work wasn't there yet. I got called away before I could finish it and hit Submit Reply much much later, without seeing your comment of having solved the issue. :confused:


But then again, at the time it didn't look like you were willing to learn at all. Since you ditched a problem when it didn't work right out of the box.....
 

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