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Pawl |
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With the help of this element you can switch on or off a hook or a sticker.
Usually a hook is directly controlled by a PLC bit. However, if there are many hooks (e.g., at a chain) that have no own identity but are only distinguished by their position it is very difficult to identify the appropriate bit. The pawl solves this problem by copying its own state to every hook it overlaps with.
Of course the bits of the hooks must be all different and unused that means that they must not be headed for by the PLC. It is most convenient to shift them to high addresses, e.g., A °10000.0, --.1, --.2 and so on. Also the bits of the hooks have to be all different, otherwise all hooks will be switched on/off at the same time.
The sample ‘tree saw’ demonstrates the use of pawls. The hooks will be activated by the first pawl if the light barrier is covered ( I 0.1, click ‘addr’ within the edit mask of the pawl to check this out.). The second pawl deactivates the hooks.
See also:
Tabsheet: Misc.
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