70 lines
2.6 KiB
Python
70 lines
2.6 KiB
Python
# *****************************************************************************
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# This program is free software; you can redistribute it and/or modify it under
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# the terms of the GNU General Public License as published by the Free Software
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# Foundation; either version 2 of the License, or (at your option) any later
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# version.
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#
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# This program is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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# details.
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#
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# You should have received a copy of the GNU General Public License along with
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# this program; if not, write to the Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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# Module authors:
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# Markus Zolliker <markus.zolliker@psi.ch>
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# Jael Celia Lorenzana <jael-celia.lorenzana@psi.ch>
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# *****************************************************************************
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"""PI control for furnance"""
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import time
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from frappy.core import Writable, Attached, Parameter, FloatRange, Readable, BoolType, ERROR, IDLE
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class PI(Writable):
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input = Attached(Readable, 'the input module')
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output = Attached(Writable, 'the output module')
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relais = Attached(Writable, 'the interlock relais')
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p = Parameter('proportional term', FloatRange(0), readonly=False)
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i = Parameter('integral term', FloatRange(0), readonly=False)
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control_active = Parameter('control flag', BoolType(), readonly=False, default=False)
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value = Parameter(unit='degC')
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_lastdiff = None
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_lasttime = 0
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def doPoll(self):
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super().doPoll()
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if not self.control_active:
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return
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self.value = self.input.value
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self.status = IDLE, 'controlling'
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now = time.time()
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deltat = min(10, now-self._lasttime)
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self._lasttime = now
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diff = self.target - self.value
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if self.value > 300:
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self.write_control_active(False)
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return
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if self._lastdiff is None:
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self._lastdiff = diff
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deltadiff = diff - self._lastdiff
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self._lastdiff = diff
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output = self.output.target
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output += self.p * deltadiff + self.i * deltat * diff
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if output > 100:
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output = 100
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elif output < 0:
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output = 0
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self.output.write_target(output)
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def write_control_active(self, value):
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if not value:
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self.output.write_target(0)
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def write_target(self, value):
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self.control_active = True
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self.relais.write_target(1)
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