A logical architecture shows the system components (and the interactions between them) that are needed to provide a specific set of services to end users. 
Logical technical architecture is considered a type of structural design that is used to provide a detailed description of the system without defining the system technology or environment.
It includes all the information related logically and detailed description without using technical terms in it.
It can be considered a diagram used to define the relation between the software components.
The main purpose of designing logical architecture is to plan for the system and use it for communication before designing and implementing the system. And by this diagram, the user can get an overview of the system.