Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 62)

Chapter 5
Developing Programs
5-2
The Application Program Interface (API) is a set of library routines used to
interface your programs with the control coprocessor. The following are
the categories of functions available in the API library.
Table 5.A
API Library Routines
API Function Definition of Set
DTL DataĆtable library (DTL) commands that access the dataĆtable memory of a
programmable controller that is directly connected (directĆconnect mode) to the
control coprocessor
BPI ControlĆcoprocessor commands accessing the dataĆtable memory of a
programmable controller through the backplane interface (BPI)
MSG ControlĆcoprocessor message (MSG) commands that handle unsolicited
Message Instructions from a programmable controller ladderĆlogic program
(directĆconnect mode)
TAG ControlĆcoprocessor commands (TAG) that provide access to the controlĆ
coprocessor memory for external devices that are connected via the serial
interface(s); ControlView R is an example of sucha device that would require
access to controlĆcoprocessor memory; TAG also provides access to
controlĆcoprocessor memory between OSĆ9 program modules
CC ControlĆcoprocessor utility commands that handle functions such as trap
initialization, error handling, ASCII displays, etc.
Use Table 5.B to determine which API functions to use for your
specific application.
Table 5.B
When to Use API Functions
For this application: Use this set of
API functions;
Access the data table of a PLCĆ5 programmable controller that is directly
connected to the control coprocessor
DTL_
Accomplishdiscrete or block transfer of data witha programmable controller
(either directĆconnect or standalone mode)
BPI_
Respond to an unsolicited programmableĆcontroller message MSG_
Provide access to controlĆcoprocessor memory for interaction among routines
running on the control coprocessor and to external devices connected via the
serial port(s)
TAG_
Provide access to controlĆcoprocessor memory for devices attached to the
serial ports
TAG_
Handle errors generated by API functions CC_
Initialize the control coprocessor (accomplish first and once only in
every program)
CC_
What Is the Application
Program Interface?
When to Use API Functions