INFICON STC-2000A Thin Film Deposition Controller Operating Manual - Manual (Page 189)

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STC-2000A DEPOSITION CONTROLLER
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different bit weights. This combined map value encodes the state of each of the possible eight
source's active deposition state. When a source is being used for an active deposit (manual,
deposit, rate-ramp, time-power, etc) phase, the associated bit weight for that source will be true.
For the case of source #1 (first of two sources on the first Source/Sensor card), the least significant
bit weight (value of 1) is used. This bit is detected via the #1 = test. Since only one source can be
active at a time (non-codeposition mode), the test for which source is in use can be a simple
equality comparison. If source two were desired, the bit weight/value would be 2. Source three
would be a value of 4, with a doubling to 8, 16, 32, 64, 128 for each higher numbered source's
shutter.
Rung 004: This rung controls a relay that can be used to operate a dual shuttered head. When sensor two is
contributing to a measurement (active mode), its bit-weight (#2) will be true in the bitmap I/O
resource #81 (XTLSHUT, or crystal shutter). Rung 4 examines the value of resource 81 (I81),
placing the combined state of all 8 sensors as a scalar value on the I/O program stack. The
constant value 2 is then stacked, and the bitwise AND operator (&) is performed, leaving either a
0 or 2 value remaining on the stack. The O10 output token evaluates the top of stack (TOS) value,
and if non-zero (in this case, 2), results in a TRUE state to resource 10 (Relay 3). If sensor two is
not being used (and most likely # 1 is), then the result will be 0 or FALSE, and the relay will not
be activated. In this way the exclusive (one or the other) use of the standard two sensor channels
can control an electrical/pneumatic/mechanical shutter to cover/expose the appropriate crystal.
Rung 005: This rung, in combination with rung #6, controls relay 4 (resource ID #11) to indicate when a
film's setpoint thickness threshold has been reached. This rung examines the event 221 (I221 for
setpoint thickness event) and when the instrument signals/triggers the internal event which
indicates the accumulated thickness has exceeded the programmed threshold, sets the relay via the
S11 token. It remains set until a subsequent clear operation is caused in rung #6 (see below),
which is at the start of a new film job. In this way the signal is a steady state throughout the
deposit phase in which it is detected and occurs. Such a relay could be used to turn on a process
variable such as heat, gas flow, etc..
Rung 006: This rung examines the occurrence of the 228 (Begin Job/Film) event via the I228 token, and on
occurrence of the event (starting up a film execution) places a TRUE value to the stack (TOS) for
one evaluation of the logic program. This single occurrence of the TRUE is used to activate the
C11 token, which clears or reset relay 4. The combined behavior of rungs 5 and 6 produce a relay
closure which lasts from the time when a deposit thickness accumulation exceeds the programmed
thickness setpoint threshold until the next film is started. Alternatively the EndJobDeposit or
EndJobFilm (230 or 231) events could be used to cancel the relay at the end of the deposit, so the
relay would be active only during the deposit cycle which closed it. Exactly what is needed is up
to the end user's requirements.
Rung 007: This rung connects (logically, cause and effect wise) the external input 1 to event 216, the
sequencing mode Start/Unconditional event. Triggering this event has the effect, if the unit is
operating in the sequencing mode, of starting the currently selected ActiveProcess. In this way a
stopped unit will start at layer 0 whether at an idle resting state or stopped in an error condition,
without the need for multiple starts as would be needed from the front panel. If the unit is in the
NON-sequencing mode, triggering this event has no effect, and this rung is harmless. It is included
in this program so the program is generic and works whether in sequencing or non-sequencing
mode. The transition of the input from FALSE to TRUE creates the edge which triggers the event.
Continued persistence in the TRUE state does nothing, and the signal must go FALSE long
enough to be sensed FALSE (minimally 1/4 second to be sure), before going TRUE again can
cause another process start. Only a process at rest can respond to the process start. Process starts
that occur while a process is already running are ignored, not queued up. Once the process stops,
the next occurring new trigger of a start event causes the process to restart.
Rung 008: This rung connects (logically, cause and effect-wise) the external input 1 to event 202, the
NON-sequencing mode Generic Start Film event. Triggering this event has the effect, if the unit is
SECTION 5.XX page 189 of 292