Operation
VTK-TR-BA-072e-1 - User Manual MDS 358X Series
7 Operation
7.1 Triggering a Dispense Sequence
There are three different options to trigger a dispense sequence:
• via keypad on the control unit MDC
Press the [trig] button, a dispensing sequence with pre-set parameters will be triggered.
• via RS-232C command
Use the command “VALVE:OPEN” (further commands in paragraph 8.1.2, page 84).
• via PLC signal
Real time triggering by direct I/O (recommended length of signal: between 0.0001 ms and
35 ms; not relevant for Infinite Mode and External Mode)
7.2 Dispensing and Positioning of Dots (Modes)
To combine a multitude of dots to a predefined structure (e.g. a line or a circle), use one of the
following modes:
• Burst Mode
A single trigger impulse by PLC signal causes a predefined number of dispense cycles.
Number of Pulses: predefined value (e.g. 1–32000)
• Single-Shot Mode
Each dispense point is triggered by an individual PLC signal. When dispensing a continuous
feature (such as a straight line or a circle), the frequency of the dispense trigger signal should
be proportional to the trajectory speed of the axis system. This is necessary to achieve a
continuous line width.
Number of Pulses: “1”
• Infinite Mode
– Continuous dispensing as long as the PLC trigger input is “logic 1”. Dispensing will stop when
the signal is changed to “logic 0”
– Number of Pulses:
– “infinite” (when programmed through keypad)
– “0” (when programmed through RS-232C)
The parameters Rising, Falling, Delay, Needle Lift and Open Time use the values preset in the
menu. Is the PLC trigger signal “logic 1”, the MDC sends dispensing impulses, until the signal
changes to “logic 0”.
• Scenario Mode
A complex set of shots is defined via a scenario. This allows the dispensing even of very
complex structures, since up to ten different segments, each with their own set of
parameters, can be combined. Four different scenarios can be saved.
The parameters are set according to the specifications of the scenarios.
• External Mode
The “External Mode” will shift the responsibility of time control of the parameter “Open Time”
to the higher-level machine control. (This may require a very precise time control of the
higher level PLC.) As a result, the valve would function like a “Time-Pressure-Valve”.
Activation of the control unit via RS-232C command by changing the pulse parameters. For
the External Mode set the Open Time to “external”.
Number of Pulses: Should be set to “1” (min delay still applies).
Open Time calculates according to: Length trigger impulse – length Rising = length Open
Time
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