Clarification: can an order update remove a horizon?

[ralienpp]

Suppose you send an order like this:

• the base only covers the first 3 nodes, up to node 90
• the rest is the horizon

Then you send an order update, to extend the base further up to 107:

• note that although the base is extended, the horizon has been removed

This looks like a special case of horizon modification https://github.com/VDA5050/VDA5050/issues/15, where the horizon is simply removed altogether.

The specification does not say this explicitly, so it is better to double-check - is the horizon set in stone, and can it be only extended? Or are such modifications as depicted here, or in issue #15, also valid?

[MaximilianPenninger]

I think this is defined clearly. In the German version it says

Die Leitsteuerung hat die Möglichkeit, die Fahrbefehle der Fahrroute „Horizon“ zu ändern.

In the English draft it says

MC has the option to make changes to the horizon by sending entirely different nodes as the new base.

For me, both say clearly, that the horizon can change. From my point of view, the word "change" of course includes "delete".

[collani-bosch]

I agree, "change" includes "delete". The alternative would be to change the nodes inside the horizon to identical nodes with edges of length zero. I think this is covered by the norm, but is more a corner case than a typically formed order.

[MaximilianPenninger]

The alternative would be to change the nodes inside the horizon to identical nodes with edges of length zero.

No, in my opinion this is no option. Think of track-guided AGVs, that are using RFID-Tags for Localization. They are typically not prepared for "non-movement-edges".

[collani-bosch]

@MaximilianPenninger: Yes, I think this leads to a lot of problems, but we haven't found anything in the norm which says "Don't do it." Do you know the section, which says this is forbidden?

[ralienpp]

Thanks for the clarification. I believe it would be a bit more reassuring if the text were edited to explicitly say that deleting a horizon is acceptable, e.g. : "MC has the option to make changes to the horizon by sending entirely different nodes, or deleting some of them."

[stephanlante]

In discussion within VDA and VDMA

[KIT-IFL]

Added the clarification to the specification in https://github.com/VDA5050/VDA5050/commit/e19cc603884eb45a15cb3c90700955ec8ed66b5e.