added drivers for small furnace

frappy_psi/picontrol.py

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