How to model a carousel that rotates into a server?

[WD0001]

The entity travels on a conveyor, and will be processed either at 1B or 2B.
Once the entity reaches 1A, it will decide whether to proceed to 1B or 2B.
The entity prefers to be processed at 2B. However, if 2A is occupied at that time, the entity will go to 1B instead.
1A/1B are attached to a carousel, so they move synchronously and swap places.
2A/2B are attached to a carousel, so they move synchronously and swap places.
Entities on the conveyor move independently from each other. The conveyor slips underneath a stopped entity.
The image below shows all of the locations where an entity can stop.

[ttarkan]

I would suggest the following solutions
Solution 1
1) You can use vehicle or worker object to "pickup" entities to 1A Node.
2) Change the worker picture to make it look like a "server" object.
3) You can keep the existing Server1 and Server2 objects.
4) For modeling processing time and any process related stuff you can make a copy of the entity when it is loaded to the "ridestation" of worker and transfer the new entity to the server object.

Solution 2 (recommended)
1) When Entity enters 1A create a transfer out constraint to stop entity moving forward. Such as a variable on modelentity =0
2) Create a Server with processing time = Task sequence
3) Enter any process related data and rule into task sequence
4) Move your worker (coursel) along the path using the task sequence.
5) When you want to transfer the entity to another object or make it continue moving along the conveyor, set the modelentity variable related to constraint condition to true.
 

Hope this helps,

Best regards