Some time ago I acquired a cannon that I subsequently mounted on a tripod-like contrivance, viz
 
I used the welded on pivot contrivance as a point of articulation...
 
Generally cannon are mounted using things called trunnions
 
Mine has no trunnions so I sort of assumed that it would not be mounted on a carriage per se.  
Now recently I was perusing the Zeugbuch Kaiser Maximilian (Book of armaments which is worth a gander).  I knew there were examples that resembled my cannon but, for reasons lost in the mists of time, I never paid much attention.
 
 
That is mine and they mounted it on a carriage.  Note that the pin affixing it to the carriage is below the body of the weapon.
 
Now generally, elevation adjustment is accomplished by use of a qizmo that lifts the rear of the cannon.  Here no vertical movement is possible.  How did they aim it?
Damn odd.
BTW this book definitively establishes a terminus ante quem of ~1500 for this type of cannon.  I have no problem dating it at ca. 1500.
Book of armaments ...
https://www.digitale-sammlungen.de/e...956?page=20,21