Search the Community

A basic photo eye object that can be used with conveyor belts. Photo eye is based on a transfer node object. It collects statistics on time in blocked state, cleared state and throughput. Transfer nodes on entered and on exited add on processes can be used as on blocking and on clearing add on processes. Photo eye has properties to define the delays for on blocked and on cleared. Photo eye will wait to complete on blocked delay to execute on blocked add on process. Similarly, photo eye will wait to complete on cleared delay to execute on cleared add on process. PE_Library.spfx

I'm making a simple simulation model of a hospital and I'm having trouble with the routing of my model. For instance, a patient first goes through ED and then to OR. if there is no room in the OR, then the patient must stay in ED. How can I model this? I don't want the patient to wait at any input or output buffer, because then it assumes that the ED bed that the patient used to stay in is now free but it actually isn't. Each bed is modeled as a server and there are more ED beds than there are OR beds. Naturally, all ED beds connect to a single transfer node, which then connect to all OR beds.

Hello, I want to simulate an evacuation network problem. When a hurricane is imminent, all people want to evacuate the hazard area to safe areas. Therefore, we have a traffic jam (congestion) on the road. So, The speed of vehicles changes based on traffic. I have a couple of questions: 1) Is there any module in the Simio to consider traffic on the road instead of considering waiting time for server or transfer node. I mean that congestion embedded on the road by decreasing the speed of entities. 2) Are there any options to consider congestion such as considering a segment of a road is decomposed into cells based on the free flow velocity and length of discrete time step. By this division, vehicles can move only to adjacent cells in unit time. The connectors between cells are dummy arcs indicating the direction of flow between cells. For example, if 5 hour takes time to drive from the beginning of the road to the end, we put transfer node after each one unite of time (server---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> server ). In the path, vehicles drive with fixed speed and path has a fixed capacity. Therefore, we can consider congestion if a vehicle wait to enter the path. I would be really happy if you could let me know how to consider congestion on the road. Thanks, Nadere

It seems the best way to achieve to what u want is to define three storage elements (called barstorage, gridstorage, sheetstorage) just before the combiner object or combiner node. Whenever an entity is put into any of these storages check the the condition u defined (i.e., exactly 4 bars, 4 grids and 8 sheets are exist in the individiual storage) is valid. If the condition is satisfied remove appropriate number entities (exactly 4 bars, 4 grids and 8 sheets) from appropriate storage by using search and remove step and transfer them to combiner object from standard library (or even combiner node object you get from forum) to combine them all. Else wait for the condition to be met. By this way you are able to collect some extra statistics from storages (averge waiting times and average number of each materials in the storage etc...).

As far as I understand I included my solution approach. You may wonder that the included logic does not seem work (it will always increases the capacity but wont decrease it). This may be due to your servers processing time or on/off shift schedules. I mean that in order to see how it works you should increase capacity by some predeterimed number (i.e., 10. Currently it is set to 1) and decrease it one each time any entity enters or departs waitingarea1 node. you may also increase run time to further see what happens. I hope this one meets your requirements. Still it will inspire you. NOTE: You should note that the unit time conversions and your problems' values. The logic triggers capacity increments or decrements each time an entity enters or departs from waitingarea1. Note also that waiting times are calculated as averages of those who wait at waitingarea1 transfer node throughout the simulation run. pharmacy_candidate solution.spfx

Maybe it's something trivial, but I want to know, a much time a transfernode is occupied by an entity, I've modeled a simple model, where the entities, wait in a transfer node until a station turns free.

The recommended approach might vary by what you are waiting for. For example if the plane is a Vehicle that will come to pick up the passengers, then the easiest approach is probably to have a Server with 0 processing time. Entities will flow through it with no delay, but then wait in the outbound transfer node for the Ride requested. If you want to wait on something more arbitrary you could direct the entity that enters an outbound transfer node to Wait for an event. Then you would have to add some logic to Fire that event (unless it is one that is already automatically fired). You should post your questions inside the Simio Insider forum where we can post screenshots and examples to provide a more complete answer.

The second problem is easy. Simply change the Execute step option highlighted above to its default "WaitUntilProcessCompleted". For the first problem, what I said is still accurate. You can easily enable homing when idle, or you can tell it to wait somewhere when idle, but you can't automatically do both. To allow you will need to provide a path so the vehicle can actually get back to transfer node 1. And you will have to add some similar logic to send the vehicle there when it is appropriate for it to go there. All of this discussion is to allow you to model exactly the behavior you have described. But as you share more details of your objective, it looks more and more like this could be easily approximated just using automatic library behavior without all this complexity. For example, the time to "pull up the man from the deep well" might just be modeled as a loading time. Every model is an approximation and a big part of effective modeling is know the correct level at which to approximate. If you would like some advice on how I would model this, please post or email me the full details of the situation you want to model and your objectives (e.g. why are you modeling it and what do you want to learn).

Unfortunately, two things that you considered problems are the things that are crucial to the model. First, the vehicle needs to move to transfer node 1 once it drops off entities at transfer node 2. That is a must. It needs to wait there until entities leave the server. Second, your assumption to have the entity and the vehicle to move concurrently is wrong. The problem would have been way easier if that was the case. The entity needs to start moving to transfer node 3 only when the transport arrives there. Think of it as a vehicle with a crane, pulling up a man from a deep well, where there is no ladder. Hence, the entity can only move up (in this case move to transfer node 3), after the vehicle gets there.

Hi, I would like an entity to wait at a certain transfer node until a server is idle. I know I am supposed to add a process to that node that says that, but I couldn't come up with an expression. Thanks in advance

I have seen this error before with transporter/entity transfers... You may have conflicting logic here.... i.e. an event occurs that triggers a token into a delay or wait step based on a condition before transfer can complete, yet during this duration another event occurs that wants the transfer to occur for a second time or the entity to be directed somewhere else...the original token is not released and destroyed first... simple solution... I used dummy nodes to shift the transporter\entities around based on a precedence constraint structure whilst clocking the time of the transporter\entity at each node. This worked like a bomb. Also, if you don't need the original token, destroy it or don't attach any processes on the line after it.

All right to start solving the problem, I created logic for both the vehicles (add-on process triggers > Loaded) to Search through the opposite loop/vehicle's SequenceTable for the DestinationNode assigned to the loaded entity. If the Search step finds the DestinationNode in that Table, it assigns the DestinationNode.ID to a temporary integer state, and sets the entity's priority to the other loop's vehicle's priority. After the Assign Step, a SetNode step is used to set the entity's destination to TransferNode1 (the node between the two loops). At the TransferNode: Upon entered, a process is triggered in which a Decide step checks whether a entity or vehicle enters the Node (Entity.Is.DefaultEntity), and if it is a DefaultEntity, a SetNode step sets the Entity's DestinationNode to the temp variable assigned earlier. I used one transfernode/no paths between the loops as I would like to force the vehicles to wait for the entity to be picked up by the other vehicle before moving on. The above logic mostly solves my initial question, but I'm struggling with one more thing: - If both vehicles want to transfer entities at the mutual transfernode, they just pause and no swapping is possible. The node's capacity is set to infinity, must I rather place a delay in one of the vehicles' transfer logic to overcome this? Find attached the model for reference purposes Model_Transfer_Question.spfx

I almost always simulate this using fillers/extractors from the extended flow library rather than directly filling a container on a vehicle/entity. It sounds like you could do this with entities or vehicles as long as your decision making for entities is as simple as you describe. If you do it with entities, you will have to write a bit of decision logic to the entity. I would recommend doing this on the 'onVisitNode' process, which would basically be a decision of 'Should I park now?'... true being to park and then wait for some event (wake him up), false being to keep on towards the destination. If you do it with vehicles, you will need to make some sort of decision request for the vehicle to go to the relevant node for pick-up. Normally this is done by an entity at a transfer node using the 'ride' step. However, riding a vehicle is about transferring into the ride station, not filling a container.... I foresee many pitfalls with this methodology! I might have time to take a crack at this later -- no promises though.

This is a very cool library, i have built two very simple examples to test before using it in a simulation in which they will represent Ship to Shore Cranes. First of all, it took me a moment to figure out that "entity destination" on my home node for the crane has to be set to "specific", can this work using "continue" ? Now, on attached example 1, the Crane picks the entity and will wait for an available vehicle to make the transfer, building a queue in the home node for the crane if there is no available vehicle. This is great since it reflects what happens in the actual operations, the crane waits for a truck to be below the crane to drop the container. crane_example1.spfx But there may be interest in simulating the crane dropping the entity into the floor and just keep unloading the ship, this means i now want to drop the entity without the vehicle being available. Is it possible to control this behaviour at will? I was looking for the option of an input buffer of some sort but for now I just add a normal node and allow the crane to drop it there it will build a queue waiting for the vehicle, this can be seen on example 2, I appreciate any ideas, crane_example2.spfx also, I tried scaling the elements and it gave me an error on height, so I was wondering what should i take into account when scaling (changing size) of this elements? I will take a screenshot next time I encounter the error. finally, I will be using this element in my simulation, and i was wondering what are the thoughts on "tulach" question: "5.) Crane and other crane components do generate a lot of data in trace. It would be nice to have possibility to swich this off just for some steps inside crane and co. I used it in a model that has a simulation time of 1 month and this made my trace impossible to filter and analyse." thanks best regards