SPI Programming Manual (G06.24+, H06.03+, J06.03+)

Introduction to SPI
SPI Programming Manual—427506-006
1-3
Subsystem Manager
Management applications use SPI to:
•
Start or stop an object (such as a Pathway terminal)
•
Change an object attribute value (such as the speed of a communications line)
•
Add a new object to the system (such as defining a logical subdevice on a
communications line)
•
Inquire whether an object is stopped or running
Subsystem Manager
Every subsystem that has an SPI control-inquiry interface includes a process that is
responsible for supporting the interface. This process is called the subsystem manager
process or subsystem manager. Management applications send SPI commands to this
process and receive responses from it.
In Figure 1-1
, a single subsystem process provides subsystem services and acts as
subsystem manager. Figure 1-2 on page 1-4 shows a management application
communicating with the subsystem manager of a multiprocess subsystem.
Communication between the management application and the subsystem manager
follows the SPI protocol. Communication between the subsystem manager and the
other subsystem processes can follow any protocol (including SPI) selected by the
subsystem.
Figure 1-1. SPI Communication With a Single-Process Subsystem
VST001.vsd
Management
Application
Subsystem
SPI Command
SPI Response
Legend
A subsystem might consist of a single process, in which case this process both provides the subsystem
services and serves as the SPI subsystem manager.