Javier PL avatar image
Javier PL asked Matthew Gillespie commented

FlexSim Run Speed Slider

Hi there,

I got a model developed in FlexSim 19.0.0 and tried to upgrade it to the latest version of FlexSim (20.0.0 and so on). The model units are defined as hours for visualization purposes, although most tasks' durations are of the order of days. After upgrading without (almost) any issue, I set the Run Speed Slider as always to sufficiently advance the model while visualizing part of the movements that take place in it (Max. Speed does not suit me, as it ends the model run almost immediately). However, it advances much more slowly than in 19.0.0 version. Then I saw this within 19.2.0 release notes:

"Changed the run speed slider to behave as a ratio of real time instead of model units per second"

Well, so I tried to create a simple day-based model and run it but, even setting the speed (via the slider) to a very high value, time passes by extremely slowly, since it behaves now as a ratio of real time.

So, my question is, does it mean that now every time I need to set a higher speed I have to use the Custom Value option in the pop-up? (That would be really annoying and would also slower the modelling in my case)

Does it make sense for the speed slider to be in accordance with that ratio? Even if model units are days?

Thanks in advance, Javi

FlexSim 19.0.0
flexsim 19.0.0run speedspeed changerun speed slider
· 2
5 |100000

Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Matthew Gillespie avatar image Matthew Gillespie ♦♦ commented ·

We updated the Run Speed slider in 20.2 so that you can specify the model unit ratio that the slider uses:

2 Likes 2 ·
1594834929074.png (8.9 KiB)
Benjamin W2 avatar image Benjamin W2 commented ·

Hi @Javier PL, was phil.bobo's answer helpful? If so, please click the red "Accept" button on their answer!

0 Likes 0 ·

1 Answer

Phil BoBo avatar image
Phil BoBo answered Matthew Gillespie commented

Do any other users have comments about this issue? We would like to hear from you.

Please add your thoughts about this issue. The change was largely brought on by discussion regarding this other Answers thread:

· 17
5 |100000

Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Phil BoBo avatar image Phil BoBo ♦♦ commented ·

One of our initial ideas was to add a realtime button that set the speed to the factor of model units that gives you 1 sim second / 1 real second.

The trouble with that idea comes when you want to then slightly adjust the slider to go faster or slower than real time. In a model with large model units, the value is very small and the slider then only has a few pixels of precision near the values you are trying to adjust.

So instead, we adjusted the calculation of the speed to always be based on simulation seconds per real second, so that you have more control over the speed near realtime. 1.0 always means real time.

Based on this discussion, it sounds like we should add a checkbox to model settings so that you can change it back to scaling on model units per real second. That way, if you are building a model in hours or days where seconds and realtime aren't important, it is easier to get more precision around your model units per real second speed instead of realtime speed.

3 Likes 3 ·
Brandon Peterson avatar image Brandon Peterson ♦ commented ·


I have had issues with this as well. In the past the slider was always model units per second and now it is not. I understand that this is helpful for some models that use larger time units but still are simulating a shorter time period and want to see things move in real time. For models that have very slow movements, events with long time periods, or long run times this really created a problem as it removed the ability to have any fine adjustment with the slider. I do understand why it was changed but there is also a very good argument for why it was the way it was for so long. I think a win-win would be to implement an option that would change it back, it could be placed in the model settings so that it would only need to be a change made once per model.

I don't know is this was the first person to complain about the problem or not but I do know that it wasn't the first person to have this problem. I think that some of this discrepancy is due to the reception that many of these complaints get. I know that it is easy to get defensive of positions that have been hammered out (sometimes enthusiastically) on the development side of things. But it is important that we don't get dismissive of complaints from people that weren't there for the initial debate. Even if we've heard their side of things before, we should remember that weren't in on that conversation and may have something new to add that wasn't considered yet.

2 Likes 2 ·
Javier PL avatar image Javier PL commented ·

After reading @Serge A thread, I understand his point but, in my view, when you set the model units to some order, let's say days, that means both that your process tasks' and operations' durations are mostly of that order and that you want time to advance faster that normal, so you no longer care about events that last seconds or minutes.

In his case, he had to set his model units to minutes for purposes that actually don't concern the model functioning itself, but the client's information. Therefore, I think that this fact turns out to be some kind of misconception from the modelling perspective, since it's a workaround to facilitate other issue which is external to the model. To my mind, the right methodology would be to convert those data to the proper units managed by the model.

In addition, in a more general sense, by defining the speed value as the ratio between simulated time and real time, we are actually putting the spotlight on ourselves rather than on the model, what is what should rule here. And of course, if your model units have been set to minutes, it's not counter-intuitive thinking that 1 minute in the model corresponds to one second in the reality.

Overall, since I also understand that in the Serge's case, setting the ratio in the traditional way may mean a laborious work of converting data units, I guess the best option would be letting the user decide by herself by some kind of checkbox that switches it (I know that also means some coding matters...)

1 Like 1 ·
pc neo avatar image pc neo commented ·

It will be nice to have an option to get back the previous behaviour. Currently if the model built are in units other than seconds, we often need to change the Run Speed every time we run the model (like in HealthCare model). This is worse when the model units are in hours, which just mean every time we run the model the Run Speed has to be changed.

1 Like 1 ·
Phil BoBo avatar image Phil BoBo ♦♦ pc neo commented ·

What do you mean that "if the model built are in units other than seconds, we often need to change the Run Speed every time we run the model"?

In what situation do you need to change the run speed more often if the model is in minutes than if it is in seconds? I don't understand.

The run speed doesn't change between model runs; it changes whenever you change it. How do the selected model units affect how often you need to change the run speed?

0 Likes 0 ·
Shankar Narayan avatar image Shankar Narayan commented ·

@phil.bobo Not sure if my trouble ticket from few months ago on similar experience matches this one or not but our model created in 19,2 version with model time units set to seconds and is a long running model (in terms of simulated days being a whole calendar year of 365 days), suddenly started to crawl when we upgraded to 20.0 version. Nothing was modified in the base model during or after upgrade. So we abandoned this move and reverted back to running in 19.2 which was giving us much quicker model completion times.

0 Likes 0 ·
Phil BoBo avatar image Phil BoBo ♦♦ Shankar Narayan commented ·

That has nothing to do with the units used by the run speed slider. That's a performance issue. In both cases, you are testing running the model at Max Speed, which makes it unrelated to this discussion.

This change was also made in version 19.2, so you are comparing two versions of FlexSim that both behave the same way with regards to the run speed slider.

0 Likes 0 ·
Show more comments