added visa device handler for a PI C-633 Stepper Motor Controller

Author: trombastic

pyscada/visa/devices/PI_C-633.py

@@ -0,0 +1,171 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from pyscada.visa.devices import GenericDevice
+from pyscada.models import VariableProperty
+from datetime import datetime
+from math import floor
+
+import logging
+
+logger = logging.getLogger(__name__)
+# -*- coding: utf-8 -*-
+"""Object based access to the PI C-633 Stepper Motor Controller
+
+
+Example::
+
+    unit = C633('ASRL/dev/ttyUSB0::INSTR')
+    unit.connect()
+    unit.disconnect()
+"""
+__author__ = "Martin Schröder"
+__copyright__ = "Copyright 2019, Technische Universität Berlin"
+__credits__ = []
+__license__ = "GPLv3"
+__version__ = "0.1.0"
+__maintainer__ = "Martin Schröder"
+__email__ = "m.schroeder@tu-berlin.de"
+__status__ = "Beta"
+__docformat__ = 'reStructuredText'
+
+import pyvisa
+from datetime import datetime
+from math import floor
+from time import sleep, time
+
+
+class C633(object):
+    _isconfigured = False
+    pos_max = -1
+    pos_min = -1
+    
+    def __init__(self):
+        self.instr = None
+
+    def connect(self, instr):
+        if self.instr is None and instr is None:
+            return
+        self.instr = instr
+    
+    def configure(self):
+        logger.debug(self.instr.query('*IDN?'))
+        logger.debug(self.instr.query('ERR?'))
+        self.instr.write('SVO 1 1')  # enable servo 1
+        logger.debug(self.instr.query('SVO?'))
+        logger.debug(self.instr.query('POS?'))
+        self.instr.write('FNL 1')  # reference move to lower limit
+        timeout = time() + 10 # 10s timeout
+        while self.instr.query('FRF?') != '1=1':
+            sleep(0.1)
+            logger.debug(self.instr.query('POS?'))
+            if time() > timeout:
+                return False
+        self.pos_max = self.parse_value(self.instr.query('TMX?'))
+        self.pos_min = self.parse_value(self.instr.query('TMN?'))
+        self._isconfigured = True
+
+    def get_value(self,stage=1):
+        pos_data = self.instr.query('POS?')
+        return self.parse_value(pos_data, stage=stage)
+    
+    def set_value(self,pos,stage=1):
+        if not self._isconfigured:
+            return False
+        if pos > self.pos_max:
+            return False
+        if pos < self.pos_min:
+            return False
+        self.instr.write('MOV %d %1.8f'%(stage,pos))
+    
+    def parse_value(self,str_data,stage=1):
+        data = str_data.split('=')
+        return float(data[-1])
+    
+    def query(self,cmd):
+        self.instr.timeout = 1000
+        self.instr.write(cmd)
+        data = []
+        while True: 
+            d = self.instr.read()
+            if d == '':
+                break
+            data.append(d)
+        return data
+
+from time import sleep
+class Handler(GenericDevice):
+    """
+    C-633 and other Devices with the same command set
+    """
+    smc = None
+    def connect(self):
+        #super(Handler, self).connect()
+        super().connect()
+        self.smc = C633()
+        if self.inst is None:
+            return
+        try:
+            logger.info(self.inst.query('*IDN?'))
+        except:
+            self.inst = None
+            return
+        self.smc.connect(self.inst)
+        #for variable in self._variables.values():
+        #    data_type, channel = variable.visavariable.device_property.upper().split(';')
+        #    self.smc.set_channel(channel=channel, data_type=data_type)
+        self.smc.configure()
+
+    def before_read(self):
+        pass
+
+    def read_data(self,variable_instance):
+        """
+        read values from the device
+        """
+        if self.inst is None:
+            return None
+        if not self.smc._isconfigured:
+            return None
+        stage = int(variable_instance.visavariable.device_property.upper())
+        return self.smc.get_value(stage)
+
+
+    def write_data(self,variable_id, value, task):
+        """
+        write values to the device
+        """
+        variable = self._variables[variable_id]
+        if task.variable_property is not None:
+            # write the freq property to VariableProperty use that for later read
+            vp = VariableProperty.objects.update_or_create_property(variable=variable, name=task.property_name.upper(),
+                                                        value=value, value_class='FLOAT64')
+            return True
+        if variable.visavariable.variable_type == 0:  # configuration
+            # only write to configuration variables
+            stage = int(variable.visavariable.device_property.upper())
+            self.smc.set_value(value,stage)
+            return value
+        else:
+            return False
+
+    def parse_value(self,result):
+        """
+        takes a string in the HP3456A format and returns a float value or None if not parseable
+        """
+        try:
+            i = 0
+            value = result[i]
+            """
+            timestamp = datetime(int(result[i+1]),
+                                 int(result[i+2]),
+                                 int(result[i+3]),
+                                 int(result[i+4]),
+                                 int(result[i+5]),
+                                 int(floor(result[i+6])),
+                                 int(round((result[i+6]%1)*1000))).timestamp()
+            """
+            return value
+        except:
+            return None
+