Table of Contents
Advertisement
FAQ (Frequently Asked Questions)
5.2
FAQs about Structuring the User Program
Can DP and DPC1 be operated at the same time?
Yes. The DP master must, however, already by in the OPERATE mode before
DPC1 functions can be used.
How many DPC1 jobs can be sent at the same time?
Per slave address, up to two DPC1 jobs can be sent at any one time, one for
reading or writing and one for alarm acknowledge.
How can I structure my user program?
There are basically three wait mechanisms that you can combine together:
You can poll with your user program, inother words, it queries the process
image cyclically.
You can use hardware events with semaphores as the wait mechanism.
You can call the DP_get_event function with a timeout value to wait for software
events.
You can also break down your user program into several threads (see also the
"ExamComp" sample program.).
What are the advantages of simply polling in the user program?
The program structure is relatively simple (assuming that your program does not
use any other interfaces that would require event handling such asDPC1). Polling
is particularly suitable when you expect a lot of data traffic due to a fast data
transmission rate and a lot of slaves with fast changing data.
218
DP Base Programming Interface for CP 5613/CP 5614
C79000-G8976-C108-02
Advertisement
Table of Contents
