Instruction manual

OM 751 Page 9 of 32
State Programming
The MicroTech II UVC takes advantage of state machine programming
to define and control unit ventilator operation. State machines define
specific states, or modes of operation for each process within the unit
ventilator (i.e. heating, cooling, etc.) and contain the specific logic for
each state. This eliminates some of the most common problems
associated with control sequences such as the possibility of simultaneous
heating and cooling, rapid cycling, etc.
State machine programming, and the unique nature of state diagrams,
can be easily used to describe unit ventilator operation, and can vastly
simplify sequence verification during unit commissioning, as well as
simplify troubleshooting. With the unique combination of state machine
programming and the LUI’s ability to allow a technician to easily
determine the active UVC state, troubleshooting the UVC can be very
simple.
The state diagrams presented in the following sections consist of
several “elements” including Super States, States, Conditional Jumps
(also called transitions) and a Transition Point. Super states are used as
a means to group two or more related states into a single control
function such as cooling, or heating, etc. States are where all the actual
work takes place, within each state the UVC enables PI-loops and other
logic sequences required to control unit ventilator operation within that
particular state, while other functions and PI-loops not needed during
that state may be disabled. Conditional jumps, or transitions, are the
DESCRIPTION OF OPERATION
Figure 6. Complete UVC - State Program
In the state descriptions below the terms saturated high and
saturated low indicate that the heating or cooling function being
described has reached 100% or 0% respectively.
logic paths used by the UVC to determine which state should be made
active, these are the “questions” the UVC will continually consider.
The transition point is simply a point through which a number of
conditional jumps meet, you can think of it as a point where a number
of questions must be considered from which the UVC then determines
which path is followed and which state is then made active.
The UVC states and super states are used to define the “normal” unit
modes, such as Off, Night Purge, Fan Only, Emergency Heat, Auto,
Cool and Heat. The UVC also supports several “special purpose” unit
modes such as Purge, Pressurize, De-pressurize, and Shutdown, which
can be forced via a network connection and override typical UVC
operation.
NOTICE
Not all states or modes are available for all UV configurations, and
some states (such as Active Dehumidification) are optional.
NOTICE