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<p>machine.</p>

<p>PLC software can be written in many different ways - ladder diagrams, SFC (<a href="page.php?w=sequential_function_chart">sequential function chart</a>s) or <a href="page.php?w=Instruction_list">statement lists</a>.</p>

<p><big>On-off control</big></p>
<p>On-off control uses a feedback controller that switches abruptly between two states. A simple bi-metallic domestic <a href="page.php?w=thermostat">thermostat</a> can be described as an on-off controller. When the temperature in the room (PV) goes below the user setting (SP), the heater</p><p>
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