merge with wip branch

frappy_psi/ls240.py

@@ -0,0 +1,105 @@
+#!/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 <markus.zolliker@psi.ch>
+# *****************************************************************************
+"""LakeShore 240 temperature monitor
+
+experimental, does not really work
+"""
+
+import struct
+from frappy.core import FloatRange, HasIodev, Readable, Parameter, BytesIO
+from frappy.errors import CommunicationFailedError
+
+SD1= 0x10
+SD2= 0x68
+FC = 0x49
+ED = 0x16
+
+STATUS_REQ = 0x49
+
+def dehex(msg):
+    return bytes(int(b, 16) for b in msg.split())
+
+def hexify(msg):
+    return ' '.join('%2.2X' % b for b in msg)
+
+
+class Ls240(HasIodev, Readable):
+    value = Parameter('sensor reading', FloatRange(unit='Ohm'))
+
+    iodevClass = BytesIO
+
+    def request(self, replylen, data='', ext=None, dst_adr=3, src_adr=2):
+        data = dehex(data)
+        if ext is None:
+            ext = len(data) > 1
+        if ext:
+            dst_adr |= 0x80
+            src_adr |= 0x80
+        if len(data) > 1:
+            length = len(data) + 2
+            hdr = [SD2, length, length, SD2]
+        else:
+            hdr = [SD1]
+        mid = [dst_adr, src_adr] + list(data)
+        checksum = sum(mid) % 256
+        msg = bytes(hdr + mid + [checksum, ED])
+        for i in range(10):
+             try:
+                 # print('>', hexify(msg))
+                 reply = self._iodev.communicate(msg, replylen)
+                 # print('<', hexify(reply))
+             except (TimeoutError, CommunicationFailedError):
+                 continue
+             return reply
+        return None
+
+    def read_value(self):
+
+        # check connection
+        self.request(6, '49')
+
+        # get diag
+        # 3C: slave diag, (what means 3E?) 
+        reply = self.request(17, '6D 3C 3E')
+        assert reply[13:15] == b'\x0f\x84'  # LS240 ident
+
+        # set parameters
+        # 3D set param (what means 3E?)
+        # B0 FF FF: no watchdog, 00: min wait, 0F 84: ident, 01: group
+        assert b'\xe5' ==  self.request(1, '5D 3D 3E B0 FF FF 00 0F 84 01')
+
+        # set config
+        # 3E set config (what means 2nd 3E?)
+        # 93: input only, 4 == 3+1 bytes
+        assert b'\xe5' ==  self.request(1, '7D 3E 3E 93')
+
+        # get diag
+        # 3C: slave diag, (what means 3E?) 
+        reply = self.request(17, '5D 3C 3E')
+        assert reply[13:15] == b'\x0f\x84'  # LS240 ident
+
+        # get data
+        # do not know what 42 24 means
+        reply = self.request(13, '7D 42 24', ext=0)
+        print('DATA', reply)
+        value = struct.unpack('>f', reply[7:11])[0]
+        print('VALUE', value)
+        return value