Rockwell Automation Allen-Bradley ControlLogix 1756-MVI Programming Reference Manual page 55

The relationship between these components, the CIP API, and the
application is shown in figure 4.2.
ControlBus
Connection
Mapping
Backplane
Device Driver
CPI API Interface
Application
Code
For more information about these components, refer to the Introduction
More
to ControlLogix Module Development, CID#X1557.
All data exchange between the application and the backplane occurs
through the Assembly Object, using the functions provided by the CIP
API. Included in the API are functions to register or unregister the
object, accept or deny Class 1 scheduled connection requests, access
scheduled connection data, and service unscheduled messages.
The backplane device driver is designed to support multi-threaded
applications. Critical sections are protected to guarantee data integrity.
Figure 4.2 1756-MVI CIP API System Data Flow Diagram
CM
Transports
CD
UCMM
MR
Assembly
Object
Application
Publication 1756-RM004B-EN-P - October 2000
CIP Messaging API 4-3
ID Object
ICP Object
NVS Object