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Rarely does a motion controller
operate completely on its own, with no input from the outside world. In
most cases, you'll need the PSMCC to wait for something to happen before
it goes into motion. The Wait Input command is used for that. The Wait
Input command is also the only instruction that allows you to jog the
motor using the JOG CW and JOG CCW inputs.
The Wait Input instruction has two modes of operation: single input,
where it only looks at one input, and multiple inputs where it can
examine up to 8 inputs at once. |
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Rising Edge - Wait until the
signal goes from low to high. This is similar to the high condition, but
the difference is important. Let's say that your signal into the PSMCC1
is one that will go high when you want motion to occur. However, the
signal remains high after the motion is complete, going low sometime
later. If you choose high as your input condition, the PSMCC will
complete the motion and start again because the input signal is still
high when it finishes the first move. If you choose rising edge, the
PSMCC will wait for the input voltage to go low, then high before
moving. |
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In Single Input mode, you must specify
the input and the voltage condition to expect. The choices are: |
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Falling Edge - The opposite of
rising edge. PSMCC waits for input voltage to go high, then low. This
command can be used to initiate a programme utilising the 'Start' button
(pre wired to input 1) on the front panel of the PSMCC. The wait for
input command would be the first line of the programme, and would ask to
wait for input 1. When executing the programme, the sequence would not
begin until the start button on the front panel was pressed. |
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High - Wait until the specified
input is at a high voltage state. This is the state an input will be in
if nothing is connected to it, so be careful if you use this condition.
If a wire comes loose, you could end up with undesired motion. |
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Low - Wait until specified
input is at a low voltage state. This happens when the input is
conducting current. If you use a momentary contact switch (normally open
type), this condition will occur when you press the button.
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Note: The start button also includes an
LED pre wired to output 1 on the PSMCC and can be used to illuminate the
start button whilst the programme is running. For example if the first
line of the programme asks for input 1 to begin the sequence and line 2
switches output 1 low, the button will illuminate once pressed. At the end
of the sequence before looping back to line 1 the output 1 must be set
high to switch the LED off again.
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Click
here to return to programming toolbox page |
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