frappy_psi.nanov: 'initial' version

- nneds some minor rework

frappy_psi/nanov.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+#  -*- coding: utf-8 -*-
+# *****************************************************************************
+# 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
+# *****************************************************************************
+"""Nanovoltmeter Keithley 2182A"""
+import time
+from frappy.core import FloatRange, HasIO, Module, Parameter, StringIO, Readable, Property, IntRange, Done
+
+
+class NanovIO(StringIO):
+    channel = Parameter('active channel nr', IntRange(0, 16), default=0, readonly=False)
+    _channel_index = -1
+    end_of_line = '\n'
+    _last_change = 0
+    _channels = None
+    pollinterval = 1
+
+    def earlyInit(self):
+        super().earlyInit()
+        self._channels = []
+
+    def register(self, channel):
+        if channel not in self._channels:
+            self._channels.append(channel)
+
+    def doPoll(self):
+        try:
+            idx = self._channel_index
+            channel = self._channels[idx]
+            reply = float(self.communicate('FETCH?'))
+            if abs(reply) > 1000:
+                print('BAD', reply)
+                return
+            channel.value = float(reply)
+        except IndexError:
+            idx = -1
+        now = time.time()
+        if now < self._last_change + 5 or (idx >= 0 and len(self._channels) == 1):
+            return idx
+        self._last_change = now
+        self._channel_index = idx = (idx + 1) % len(self._channels)
+        self.channel = self._channels[idx].channel
+        result = self.communicate(';SENS:CHAN %i;:SENS:CHAN?' % self.channel)
+
+
+class Volt(HasIO, Readable):
+    channel = Property('channel', datatype=IntRange(1, 16))
+    value = Parameter('Voltage1', FloatRange(unit='V'))
+
+    ioClass = NanovIO
+
+    def initModule(self):
+        super().initModule()
+        self.io.register(self)
+
+    def read_value(self):
+        if self.io.channel == self.channel:
+            self.io.doPoll()  # trigger read
+        return Done