106 lines
3.3 KiB
Python
106 lines
3.3 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# *****************************************************************************
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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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# *****************************************************************************
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"""LakeShore 240 temperature monitor
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experimental, does not really work
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"""
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import struct
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from frappy.core import FloatRange, HasIodev, Readable, Parameter, BytesIO
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from frappy.errors import CommunicationFailedError
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SD1= 0x10
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SD2= 0x68
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FC = 0x49
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ED = 0x16
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STATUS_REQ = 0x49
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def dehex(msg):
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return bytes(int(b, 16) for b in msg.split())
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def hexify(msg):
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return ' '.join('%2.2X' % b for b in msg)
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class Ls240(HasIodev, Readable):
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value = Parameter('sensor reading', FloatRange(unit='Ohm'))
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iodevClass = BytesIO
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def request(self, replylen, data='', ext=None, dst_adr=3, src_adr=2):
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data = dehex(data)
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if ext is None:
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ext = len(data) > 1
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if ext:
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dst_adr |= 0x80
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src_adr |= 0x80
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if len(data) > 1:
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length = len(data) + 2
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hdr = [SD2, length, length, SD2]
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else:
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hdr = [SD1]
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mid = [dst_adr, src_adr] + list(data)
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checksum = sum(mid) % 256
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msg = bytes(hdr + mid + [checksum, ED])
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for i in range(10):
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try:
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# print('>', hexify(msg))
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reply = self._iodev.communicate(msg, replylen)
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# print('<', hexify(reply))
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except (TimeoutError, CommunicationFailedError):
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continue
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return reply
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return None
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def read_value(self):
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# check connection
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self.request(6, '49')
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# get diag
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# 3C: slave diag, (what means 3E?)
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reply = self.request(17, '6D 3C 3E')
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assert reply[13:15] == b'\x0f\x84' # LS240 ident
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# set parameters
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# 3D set param (what means 3E?)
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# B0 FF FF: no watchdog, 00: min wait, 0F 84: ident, 01: group
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assert b'\xe5' == self.request(1, '5D 3D 3E B0 FF FF 00 0F 84 01')
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# set config
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# 3E set config (what means 2nd 3E?)
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# 93: input only, 4 == 3+1 bytes
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assert b'\xe5' == self.request(1, '7D 3E 3E 93')
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# get diag
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# 3C: slave diag, (what means 3E?)
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reply = self.request(17, '5D 3C 3E')
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assert reply[13:15] == b'\x0f\x84' # LS240 ident
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# get data
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# do not know what 42 24 means
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reply = self.request(13, '7D 42 24', ext=0)
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print('DATA', reply)
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value = struct.unpack('>f', reply[7:11])[0]
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print('VALUE', value)
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return value
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