# Initial and final affect for timed periodic event in ModelingToolkeit
**URL:** https://discourse.julialang.org/t/initial-and-final-affect-for-timed-periodic-event-in-modelingtoolkeit/119849
**Category:** Modelling & Simulations
**Tags:** modelingtoolkit
**Created:** [September 25, 2024, 9:02am UTC](https://discourse.julialang.org/t/initial-and-final-affect-for-timed-periodic-event-in-modelingtoolkeit/119849 "2024-09-25T09:02:09Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@jmaedler](https://discourse.julialang.org/u/jmaedler)
#### Post date: [September 25, 2024, 9:02am UTC](https://discourse.julialang.org/t/initial-and-final-affect-for-timed-periodic-event-in-modelingtoolkeit/119849/1 "2024-09-25T09:02:09Z")
Hi everyone,
I am working on an adapter for virtual commissioning using [ModelingToolkit.jl](https://github.com/SciML/ModelingToolkit.jl). More specifically, I use discrete callbacks (timed → periodic) to read inputs from and write output to a soft-controller. Is there a way to set the `initial_affect` and the `final_affect` arguments from [DiffEqCallbacks.jl](https://github.com/SciML/DiffEqCallbacks.jl) using [ModelingToolkit.jl](https://github.com/SciML/ModelingToolkit.jl)? Here is my MWE:
```julia
using ModelingToolkit, DifferentialEquations
using ModelingToolkit: t_nounits as t, D_nounits as D
function affect!(integ, u, p, ctx)
println("Time: $(integ.t)")
end
@mtkmodel SimpleSystem begin
@parameters begin
m = 1.0
end
@variables begin
y(t) = 0.0
end
@equations begin
D(y) ~ m
end
@discrete_events begin
1 => (affect!,[],[],[],nothing)
end
end
@mtkbuild sys = SimpleSystem()
prob = ODEProblem(sys, Pair[], (0, 10.0))
sol = solve(prob)
```
If you run this code the event will not be triggered for t = 0.0 nor 10.0. If explicitly add additional events like this:
```julia
@discrete_events begin
[0,10] => (affect!,[],[],[],nothing)
1 => (affect!,[],[],[],nothing)
end
```
both events will be called twise. I guess this is related to the solver starting at some \Delta t in the first case (and thus overstepping 0.0) and being forced to start with 0.0 in the second case. Is there currently a way arround this behavior in [ModelingToolkit.jl](https://github.com/SciML/ModelingToolkit.jl)?
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [September 25, 2024, 9:51am UTC](https://discourse.julialang.org/t/initial-and-final-affect-for-timed-periodic-event-in-modelingtoolkeit/119849/2 "2024-09-25T09:51:11Z")
Can you open an issue? There’s explicit handling in events for DiffEq for initial and final, but I’m not sure we’ve made those into options with MTK yet.
---
### Author:  [@jmaedler](https://discourse.julialang.org/u/jmaedler)
#### Post date: [September 25, 2024, 9:52am UTC](https://discourse.julialang.org/t/initial-and-final-affect-for-timed-periodic-event-in-modelingtoolkeit/119849/3 "2024-09-25T09:52:22Z")
Ok, I will.
---
### Author:  [@jmaedler](https://discourse.julialang.org/u/jmaedler)
#### Post date: [September 25, 2024, 9:57am UTC](https://discourse.julialang.org/t/initial-and-final-affect-for-timed-periodic-event-in-modelingtoolkeit/119849/4 "2024-09-25T09:57:30Z")
Done! Thanks, Chris!
>
>
> \*\*Question❓\*\*
>
> Hi everyone,
>
> I am working on an adapter for virtual commissi…oning using \[ModelingToolkit.jl\](https://github.com/SciML/ModelingToolkit.jl). More specifically, I use discrete callbacks (timed --\> periodic) to read inputs from and write output to a soft-controller. Is there a way to set the \`initial\_affect\` and the \`final\_affect\` arguments from \[DiffEqCallbacks.jl\](https://github.com/SciML/DiffEqCallbacks.jl) using \[ModelingToolkit.jl\](https://github.com/SciML/ModelingToolkit.jl)? Here is my MWE:
>
> \`\`\`julia
> using ModelingToolkit, DifferentialEquations
> using ModelingToolkit: t\_nounits as t, D\_nounits as D
>
> function affect!(integ, u, p, ctx)
> println("Time: $(integ.t)")
> end
>
> @mtkmodel SimpleSystem begin
> @parameters begin
> m = 1.0
> end
> @variables begin
> y(t) = 0.0
> end
> @equations begin
> D(y) ~ m
> end
> @discrete\_events begin
> 1 =\> (affect!,\[\],\[\],\[\],nothing)
> end
> end
>
> @mtkbuild sys = SimpleSystem()
> prob = ODEProblem(sys, Pair\[\], (0, 10.0))
> sol = solve(prob)
> \`\`\`
> If you run this code the event will not be triggered for t = 0.0 nor 10.0. If you explicitly add additional events like this:
>
> \`\`\`julia
> @discrete\_events begin
> \[0,10\] =\> (affect!,\[\],\[\],\[\],nothing)
> 1 =\> (affect!,\[\],\[\],\[\],nothing)
> end
> \`\`\`
>
> both events will be called twise. I guess this is related to the solver starting at some $\\Delta t$ in the first case (and thus overstepping 0.0) and being forced to start with 0.0 in the second case. Is there currently a way arround this behavior in \[ModelingToolkit.jl\](https://github.com/SciML/ModelingToolkit.jl)?