Siemens S7-1200 and Timers

[quadPLC]

Hey guys,

I am trying to 'seal' in a timer to execute some logic on a one-shot.

Below is a screenshot of what I have set up thus far...

What's nice is that it starts running on the one-shot, and continues to run until the timer expires. However, the -(S)- doesn't latch.

It seems like a race condition because the timer expires, turning on Q, and forcing the lower branch off. But I'd expect the timer to RLO true for at least one scan...

Am I way off base here?

This is an S7-1214 on FW2.0.2 (ick!), using TIA V11 SP2.

 

[Mike_RH]

Why not use #Lift_Waste_Gate_1 instead of the timer Q bit?

 

[quadPLC]

Ahh, that makes sense.

Only issue is that right below this logic, I do the same thing in reverse (basically, I let #Lift_Waste_Gate_1 stay on for 1 second and then turn it back off).

Without a second control signal, #Lift_Waste_Gate_1 just toggles on and off constantly.

I want it to trigger the timer when #Lineshaft_Delay_Complete comes on, wait #Conveyor_1_Delay, latch #Lift_Waste_Gate_1 on for a second, and then turn off.

I feel like maybe I am not using the right blocks for this purpose. Square peg, round hole and all that...

 

[quadPLC]

Sorry for double-post but this is a solution that works. Not as nice looking, but seems to work okay:

I know the #Lineshaft_Complete signal is an OSR so I am not too worried about it re-triggering the timer.

 

[balash]

why not use a Pulse Timer?
don't have a laptop her but here's a sketch...

EDIT:
I forgot, IN is OSR LineshaftDealy

 

[BryanG]

As balash says, you are reinventing the wheel, depending on the version of TIA Portal you are using you should have timer of type TP that does what you want. If that isn't available then look at a TOF timer and add a Rising Edge bit to start it.

 

[quadPLC]

@Balash: That's terrific, just what I needed. Glad to add something other than the TON to my repertoire

Bryan, thanks for the comments as well. Looks like it's working great and I cut the number of networks in half!