adding files

my-emco/comms.py

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+#!/usr/bin/env python
+# list available ports with 'python -m serial.tools.list_ports'
+import serial
+import watchdog
+
+## Default values ##
+BAUDRATE = 38400
+"""Default value for the baudrate in Baud (int)."""
+
+PARITY   = 'N' #serial.PARITY_NONE
+"""Default value for the parity. See the pySerial module for documentation. Defaults to serial.PARITY_NONE"""
+
+BYTESIZE = 8
+"""Default value for the bytesize (int)."""
+
+STOPBITS = 1
+"""Default value for the number of stopbits (int)."""
+
+TIMEOUT  = 0.05
+"""Default value for the timeout value in seconds (float)."""
+
+CLOSE_PORT_AFTER_EACH_CALL = False
+"""Default value for port closure setting."""
+
+
+class Message:
+   """'container for messages. keeps two strings <message> and <value>"""
+   def __init__(self, name = '', data = ''):
+      self.name = name
+      self.data = data
+      
+   def __repr__(self):
+      return 'msg: ' + self.name + ' val: ' + self.data
+
+   def copy(self, msg):
+      self.name = msg.name
+      self.data = msg.data
+
+class instrument:
+   """rs232 port"""
+
+   def __init__(self, 
+                port, 
+                msg_handler, 
+                watchdog_enabled = False, 
+                watchdog_timeout = 2,
+                watchdog_periodicity = 0.5):
+      self.serial = serial.Serial()
+      self.serial.port = port
+      self.serial.baudrate = BAUDRATE
+      self.serial.parity = PARITY
+      self.serial.bytesize = BYTESIZE
+      self.serial.stopbits = STOPBITS
+      self.serial.xonxoff = False       # disable software flow control
+      self.serial.timeout = TIMEOUT
+      self.portOpened = False
+      self.msg_hdlr = msg_handler
+
+      self.watchdog_daemon = watchdog.WatchDogDaemon(watchdog_timeout,
+                                                     watchdog_timeout,
+                                                     watchdog_enabled)
+      self.watchdog_daemon.reset = self._watchdogClose #register watchdog reset function
+      self.closed_by_watchdog = False
+
+      self.open()
+
+   def open(self):
+      try:
+         self.serial.open()
+         self.portOpened = True
+         print 'comms::opening port'
+      except serial.SerialException:
+         self.portOpened = False
+         print 'unable to open port...'
+
+   def close(self):
+      self.serial.close()
+      self.portOpened = False
+      print 'comms::closeing port'
+
+   def dataReady(self):
+      if self.portOpened:
+         return self.serial.in_waiting     
+      else:
+         return False
+         
+   def readMessages(self):
+      """reads serial port. creates an array of events
+      output: array of events: 
+      """
+      if self.closed_by_watchdog:
+         self.closed_by_watchdog = False
+         self.open()
+
+      while self.dataReady():
+         msg_str = self._read().split('_', 1)
+
+         if msg_str[0] != '':
+            self.msg_hdlr(Message(*msg_str))
+            self.watchdog_daemon.ping()
+
+   def generateEvent(self, name, data = ''):
+      self.writeMessage(Message(name, data))
+
+   def writeMessage(self, m):
+      self._write(m.name)
+      if  m.data != '':
+         self._write('_' + str(m.data))
+      self._write('\n')
+
+   def enableWatchdog(self, enable):
+      self.watchdog_daemon.setEnabled(enable)
+
+   def _write(self, str):
+      if self.portOpened == True:
+         #serial expects a byte-array and not a string
+         self.serial.write(''.join(str).encode('utf-8', 'ignore'))
+     
+   def _read(self):
+      """ returns string read from serial port """
+      b = ''
+      if self.portOpened == True:
+         b = self.serial.read_until() #blocks until '\n' received or timeout
+         
+      return b.decode('utf-8', 'ignore')        #convert byte array to string
+
+   def _watchdogClose(self):
+      self.closed_by_watchdog = True
+      self.close()
+
+   def _is_number(self, s):
+      """  helper function to evaluate if input text represents an integer or not """
+      try:
+         int(s)
+         return True
+      except ValueError:
+         return False