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TPM
EasyPAC User Manual
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'Busy' output indicates that the FB is not finished. 'Busy' is SET at the rising edge of 'Execute' and RESET
when one of the outputs 'Done', 'Aborted', or 'Error' is set. It is recommended that this FB should be kept in the
active loop of the application program for at least as long as ‘Busy’ is true, because the outputs may still
change. For one axis, several Function Blocks might be busy, but only one can be active at a time.
Output ‘Active’
The 'Active' output is available on Function Blocks with buffering capabilities. This output is set at the
moment the function block takes control of the axis. For unbuffered mode the outputs “Active” and “Busy”
can have the same value.
Enable and Valid / Status
The 'Enable' input is coupled to a 'Valid' output. 'Enable' is level sensitive, and 'Valid' shows that a valid set of
outputs is available at the FB. The 'Valid' output is TRUE as long as a valid output value is available and the
'Enable' input is TRUE. The relevant output values are refreshed while the input 'Enable' is TRUE. If there is a
FB error, the output is not valid (“Valid” set to FALSE). When the error condition disappears, the values will
reappear and 'Valid' output will be set again.
The behavior of the “Execute” / “Done” style FBs is as follows:
Figure 6-71: the FB behavior
6.6.4. Why the Command Input Is Edge Sensitive
The “Execute” input always triggers the function with its rising edge. New input values may be commanded
during execution of a previous command because the inputs are only read once. The 'Done' output can be used
to trigger the next part of the movement. The example given below is intended to explain the behavior of the
Function Block execution.
The figure illustrates the sequence of three Function Blocks, 'First', 'Second' and 'Third', controlling the same
axis. These three Function Blocks could be for instance various absolute or relative move commands. When