# Designing of Machine Backups in Reconfigurable Manufacturing Systems
## 2 Materials and Methods
The method writes via the MS Excel parameter for the volume of the product types to the input tables (TABk1 to TABk10) for each product type separately. For example, product K1 is product volume = 450 (in the first iteration), but in the next iteration of this methodology, it is product value = 150; this parameter is written down to element TABk1. For product, K2 is situation equal, and the product volume is written down to element TABk2 etc. After starting the simulation, these values are generated on the input, from where they pass to the element S_VS1. The element contains the output rule defined by the Md1 method and the input variables k1 to k10. The variables determine the state of the product transition through the operating stage based on data from MS Excel. The method assesses the transition of a given product to the production stage on the basis of an acquired value of 1 or 0. If the product does not pass through the operating stage, it proceeds to the next element, S_VS2. If the variable reaches the value 1, the product will be processed at the operational stage, and thus proceeds to the element VS_1. The following element addresses the product only to the required number of devices based on the input data for the given production/operating stage. In this case, this is decided by the proposed method MVS1. Based on the value of the variable VS1, this method determines the path of the product to a specific material flow distributor (elements FC1 to FC19). The distributor element determines the number of machines used for processing products for the operating stage. If necessary, e.g., two devices, the products will go to the FC2 distributor; if necessary, three  
Figure 3:1 Schematic representation of the created simulation model. devices, the products will go to the FC3 distributor, etc. When one machine is needed, the products proceed directly to the machine element S1. Another critical part of the simulation model is determining and recording operating times for specific products. Thus, the Mvst1 method reads the necessary data on the operating times processed at the production stage and writes them to be defined in the element table TABvst1. The table elements are permanently assigned to each machine in each stage, so the machines identify the operating time based on said table elements. The next part is the Mt method, which, based on the SimulationTime variable, overwrites the simulation time with the time defined for the product family \(T\alpha\). After starting the simulation, the last method Mo is activated, which has the task of writing the final volume of processed products into the variable Output. The result is then read back into MS Excel as the value \(n_{sp}\). The resulting simulation model proposed in the Tecnomatix Plant Simulation software v. 14.2, Educational is shown in Figure 3:2  
(c) The last part of the simulation was the creation of data exchange of the simulation model and MS Excel via DDE. The simulation model is subject to the MS Excel package procedures using DDE. The functionality of the mentioned dynamic exchange is based on the execution of individual methods and direct writing of the determined values of MS Excel into the defined simulation variables. In MS Excel, the condition \(n_{z}\geq n_{sp}\) (6) is then verified from the algorithm shown in Figure 4; if the condition is met \(n_{z}=n_{sp}\), the calculation continues to the next part of the module (in our case section C in text). C, the third part of the creation of the product family describes the backup calculations for the specified product family (Figure 8), while the availability of resources/equipment for this family is also determined in parallel. The calculation of the backup machine is based on the failure rates that occurred during the manufacturing of the previous product family. Suppose a fault has occurred in the set of machines in the previous iteration. In that case, there is a higher probability that this fault will occur again. Therefore, it is necessary to create a reserve in a backup machine.