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How to define a normal distributed process time with changable variables

 

Hello community,

I have a rather simple question/problem which I still can't find the solution for:

 

I want to define the process time of an assembly station which the help of two variables, which the user can change in the modell, so that it is normal distributed.

(First variable being the user-defined "basic process time", second variable being a user-defined "time-factor" that get's multiplied with the "basic process time".)

When using a constant process time, the definition (called in the init-method at the start of the simulation) is quiet simple:

 

Assembly_Station.ProcTime := "basic process time" * "time-factor"

 

But when trying the same with the normal distributed process time, the time only gets calculated once and the stays that value, instead of changing for every entering MU.

 

init method:

var X:time := "basic process time" * "time-factor"
var Y:time := ("basic process time" * "time-factor") / 2

Assembly_Station.ProcTime := z_normal(9, X, Y, 0, 100)

 

Does any one know how I can define the process time in such a way?

 

Thanks in advance!

 

 Edit: corrected data type

2 REPLIES

Betreff: How to define a normal distributed process time with changable variables

Siemens Legend Siemens Legend
Siemens Legend

You need to assign the sub-attributes: (set your Processing Time in the station to "Normal" first)

 

var X :time := 2:00

var Y : time := 30

Station.procTime.mu := X
Station.procTime.sigma := Y
Station.procTime.lowerBound := 0
Station.procTime.upperBound := 5:00

 

Another solution is to use your method as a "Formula" in the station. Then it is recalculated for every process when a new mu enters. Less performant but more flexible. Needs a return value "time":

 

--> time

return := z_normal(1, X, Y, 0, 5:00)

Betreff: How to define a normal distributed process time with changable variables


Thank you, that was helpful!