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Comparison - Accumulating / Non-Accumulating Conveyor using Line vs Buffer


I am trying to represent accumulating / non accumulating conveyor using buffer and I did the attached model to make sure Buffer can replace Lines to represent that.


When the accumulating checkbox is checked, the results are the same but when it is unchecked there is a deviation in the result (0,4jph) compared with Line.


Shouldn't the results be the same for both situations??? (see the report of the experiment manager in the model)


Betreff: Comparison - Accumulating / Non-Accumulating Conveyor using Line vs Buffer

Gears Phenom Gears Phenom
Gears Phenom

Hi Ricardo,


turn off the failures for your 4 SingleProcs and run the model. The throughput will be the same. Due to the random failures, your 2 production lines are not operating perfectly equal, which causes the difference in the results.


If you connect the SingleProcs before and after the line with a LockOutZone and only apply the failure-profile to the SingleProcs of the above production-line (see attached model), you can test the behavior better. Now you will again see a difference in throughput, even though the SingleProcs were failed/stopped at exactly the same times for exactly the same duration.


Now note that both your line/buffer have capacity 16, but your line has a length of 15m and your MU's are 1m long. So physically there can never be 16 MU's on the line, but on the buffer it could be possible! However, changing this does not resolve the different throughput (the non-accumulating line/buffer are never completely full, anyway).


Now I've debugged through it and came upon a certain situation, where the 2 lines start to behave differently (I've saved the model at the time, but you can also restart the model, it will automatically stop shortly before the situation). There are 2 MU's completely at the end of the line/buffer and a 3rd one blocked at its entrance. Now when the failure ends and the exit-SingleProcs continue producing, the 3rd (now 2nd) MU on the line is allowed to move up 1 position together with the other MU, while on the buffer only the last MU is allowed to move up.


From my point of view, this is a bug in Plant Simulation. What license do you use, can you report bugs to Siemens yourself?




Alex Dilg, Consultant at SimPlan AG (
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Betreff: Comparison - Accumulating / Non-Accumulating Conveyor using Line vs Buffer


another opinion about why the use of similar objects report different results (exemple in discution)?