INFICON STC-2002 Thin Film Deposition Controller Operating Manual - Manual (Page 156)

p STC-2002 DEPOSITION CONTROLLER y
SECTION 5.XX e page 154 of 276 ^
Truth Table Notation
When using Boolean operators, it is common to use a truth table, (Refer to Table 5.3). This shows
all possible combinations of inputs and the resulting outputs. Let's assume that we have 2 input terms
called A and B, and the output term is called C. The operator symbols for 'AND', 'OR' and 'NOT' are
& ,
¦, and ! , respectively. For the following table, we will use TRUE (T) and FALSE (F) to indicate Boolean
states.
& (AND)
¦ (OR) ! (NOT)
A & B = C A ¦ B = C ! A = C
T T T
T F F
F T F
F F F
T T T T F
T F T F T
F T T
F F F
Table 5.3: Truth Table.
STC-2002 States and Events
You are already familiar with states of the STC-2002. Some of them appear on the RunTime
screen and appear as large characters. Common states are STOPPED, DEPOSIT, RISE 1, etc. States are
just a period of time in which the STC-2002 does a particular task. There are many internal states into
which you have access with the I/O program. It is not necessary to fully understand the internal workings
of the STC-2002 in order to write an I/O program, however. By examining the examples later in this
section, you can get a good idea of what is needed.
State Diagram Notation
In writing an I/O program, you can test whether a state is active or not. Events cause something to
happen in the STC-2002. An example of an event is pushing the START key. In state diagram notation,
events are the lines connecting states together. The I/O system can force events in the STC-2002. Refer to
Table 5.4, a list of all of the states and events the I/O system can access. You may want to copy this table
and keep it handy as you go through the examples. It provides a key to the codes in an I/O program. Four
front panel LEDs (output) and four fixed front panel keys (input) have been assigned ID's which allow
them to be incorporated into an I/O program
(Table 5.6,#64-71) .
SECTION 5.3