Introduction | Object List | Bitmap | Array of Object Numbers
Using Lists, Bitmaps, & Arrays | Application-MPI-Controller Interface

Three Ways to Associate Objects with Objects

Object	.	When to Use
List	an ordered list	Use a List when the order of the objects to be associated is important, OR when some of the objects reside on different controllers.
Bitmap	an un-ordered list	Use a bitmap when the order of the objects is not important, AND the objects must all reside on the same controller (same Control object).
Array of object numbers	an ordered list	Use an array of object numbers when the order of the objects is important, AND the objects must all reside on the same controller (same Control object).

Object List

Use an object list to associate objects when ordering is required, such as the Axis list maintained by a Motion object. For example, when using a Motion object, a list of Axes 0, 1, 2 is not the same as a list of Axes 0, 2, 1. Such a distinction is not available when using an object map. Refer to the List methods for Motion, Notify, Sequence and EventMgr objects.

This object:	Can have object lists of:
Motion	Axes
Notify	Events
EventMgr	Controls Notify objects
Sequence	Commands

Bitmap

An object map is a bitmap, where each numbered bit represents the presence or absence of the correspondingly numbered object. You can order the objects in the bitmap from numeric low-to-high or high-to-low, but there is no other meaningful capability for ordering objects with an object map.

Another consideration with object maps is that all objects specified in the map and the object (that those objects are being associated with) must be resident on the same controller (Control object).

Note: Although the MPI allows an Axis to be associated with a Motion without regard to the controller (Control), the XMP implementation of the MPI does not allow this.

Object maps tend to be used to associate low-level objects that:

must all reside on the same controller (Control) and the order in which the objects are ordered does not matter

Note that the objects specified in the bitmap may be associated with another object, without those objects having to be created and deleted. A goal of the MPI has been to minimize the need to create and delete objects, especially objects that are just used for configuration. For example, an MPI application that uses the default configuration doesn't have to create Filter or Motor objects, yet the application can still configure an Axis, by calling mpiAxisFilterMapSet(...), where the Filters are specified by the bitmap.

Object Maps for Objects

This object:	Has associated object maps of:
Filter	Axes Motors
Axis	Filters Motors
Motor	Filters Axes Adcs

Array of Object Numbers

The MPI provides a third means of associating objects, by using object numbers. Object numbers should be used when ordering is required, and all the resources arelocated on the same controller.

Using List, Bitmaps, & Arrays

Application-MPI-Controller Interface