High Country Tek emc-3L - Manual (Page 49)

4 Bubble Logic
DVC710 application programs consist of one or more
code sections. The first section is called the Always
code and the second and additional sections are called
logic sequences. An icon in the main project window
identifies each of the sections. These icons represent
where the programmer actually writes the application
code. Each application has an Always section and
optionally any number of logic sequence sections. By
clicking the right mouse button in the project window, a
menu will appear that will allow the addition of logic
sequence icons.
A logic sequence is composed of “logic bubbles” that
contain application code. Code expressions specifying
under what circumstances execution will transition to
another bubble are also present as the diagram
illustrates. Typical transition conditions are a timer
expiring or digital input being true.
Logic sequences, Bubble transitions and the Always
code have a defined way in which they are executed.
The Always code is executed followed by the code for
the active bubble in a logic sequence and finally the
outbound transitions defined for the active bubble are
evaluated. If one of the transition expressions is true
the bubble pointed to by that transition will be the new active bubble the next time the logic sequence is
executed. Upon completing this cycle, the Always code is executed again and the active bubble for a different
logic sequence and its transitions are executed and evaluated respectively if more than one logic sequence is
defined. After the last logic sequence is executed the first one will be executed during the next cycle. This
Always code - logic sequence – transition evaluation cycle is repeated every 10ms or longer if the code is
complex. In between these cycles, the DVC710 BIOS executes and records system input/output value changes
and sends and receives CAN Bus messages. Given the
frequent execution of the Always code it should contain
your system critical code such as code to sound an
alarm control critical valves. Note that the timing
between executing each logic sequence is a minimum
of 10ms times the number of logic sequences. Logic
sequence code is usually where your normal system
operation sequences and display code are programmed
(i.e. open this valve when this digital input is switched
on).
Note that with release 5.2, the above cycle sometimes
referred to as the system heartbeat can be set from 1ms
to 20ms with the default being 10ms.
To further help you control the operation of your
application from a timing perspective Logic sequences
can be grouped to provide you a way of tuning the
performance of your system while maintaining the logic
sequence coding paradigm for different aspects of your
Intella Programming Too with Logic Sequence
Screen and Bubble Logic
P/N: 021-00163, Rev. A.0 - for V5.2 Tools Page | 49
Intella Programming Too with Logic Sequence
Screen and Bubble Logic