About Resource Groups
You cannot use a resource group on an operation unless it has at least one resource assigned to it.
How the Scheduler Assigns Resources
The Scheduler assigns an available resource to the load based on allocation rules you define (such as "choose the resource that has been idle the longest"). Depending on the allocation rules defined, various factors may affect how the Scheduler selects one of the member resources over the others. The Seq field on the Resources tab is important, especially when using The "Select in Sequence" and "Cyclic" Allocation Rules because they allocate the resource with the lower Seq value first.
See Using Scheduler Rules for more information.
How APS Assigns Resources
APS selects resources from the resource group based on the best combination of resources from all resource groups required for the operation. In this case, "best" means the combination that allows the operation to be planned the fastest.
For example, an operation may require 1 resource from labor resource group "Drillers" and 1 from machine resource group "Drill." Each of these resource groups contains five resources that could do the work. The system starts at the top of the list of resources defined for each group and, for each resource, examines information such as shift availability and whether the resource is already busy on other jobs.
The Seq field on the Resources tab is important because it determines the sequence of the resource list and can affect which resource the system chooses in the case of "ties."
How to Assign a Specific Resource
To assign a specific resource to work on an operation, create a resource group that contains only that resource. On the Operation record, reference that resource group on the Resources tab.