diff -r a04bea92c509 -r 78e3e839658b prologix.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/prologix.py	Mon Dec 17 18:59:45 2007 +0100
@@ -0,0 +1,117 @@
+"""
+Prologix
+========
+
+Module defining a communication object to talk to Prologix USB-GPIB controler.
+
+"""
+import serial
+import time
+
+import gpib
+from gpib import ConnectionError
+
+GPIB_CONTROLLER = 1
+GPIB_DEVICE = 0
+
+class GPIB(object):
+    _retries = 15
+    def __init__(self, device="/dev/ttyUSB0", baudrate=115200, timeout=0.1,
+                    address=0, mode=1):        
+        """
+        Create a new GPIB controller for the Prologix USB-GPIB device
+        located on serial device 'device'.        
+        """
+        self._cnx = serial.Serial(port=device, baudrate=baudrate, timeout=timeout)
+        self._timeout = timeout
+        
+        self.set_mode(mode)
+        self.set_address(address)
+        
+    def set_address(self, address):
+        """
+        Set the address of the GPIB device:
+        
+        - if the device is the Controller In Charge, this is the
+          address of the device commands are sent to,
+
+        - if the device is in GPIB_DEVICE mode, this is its address.
+        """
+        self._set_cmd('addr', address)
+        self._adress = address
+        
+    def set_mode(self, mode):
+        """
+        Set GPIB device mode to 'mode':
+        
+        - GPIB_CONTROLLER: set the device as the Controller In Charge
+          on the GPIB bus
+
+        - GPIB_DEVICE: set the device as a standard GPIB device on the
+          bus.
+        """
+        self._set_cmd('mode', mode)
+        self._mode = mode
+
+    def set_controller(self):
+        """
+        Set GPIB device the Controller In Charge on the GPIB bus.
+        """
+        self.set_mode(1)
+
+    def set_device(self):
+        """
+        Set the GPIB device as a simple device on the GPIB bus.        
+        """
+        self.set_mode(0)
+
+    def send_command(self, cmd):
+        """
+        Send the specified GPIB command on the bus (must be the CIC),
+        and read the answer.
+        """
+        assert self._mode == 1
+        self._cnx.write(cmd+'\r')
+        time.sleep(self._timeout) # required?
+        ret = self._cnx.readlines()
+        return ''.join(ret)
+
+    def check_srq(self):
+        """
+        Check the SRQ line
+        """
+        assert self._mode == 1, "must be the Controller In Charge"
+        self._cnx.write('++srq\r')
+        ret = self._cnx.readline().strip()
+        if ret:
+            return bool(int(ret))
+        return None
+
+    def poll(self):
+        """
+        Poll every address, and return a dictionnary
+         {add: status, ...}        
+        """
+        assert self._mode == 1, "must be the Controller In Charge"
+        dico = {}
+        for add in range(31):
+            self._cnx.write('++spoll %d\r'%i)
+            ret = self._cnx.readline().strip()
+            if ret:
+                dico[i] = int(ret)
+        return dico
+    
+    def _read(self):
+        for i in range(self._retries):
+            rdata = self._cnx.readline()
+            if rdata.strip() != "":
+                break
+            time.sleep(self._timeout)
+        return rdata
+
+    def _set_cmd(self, cmd, value):
+        self._cnx.write('++%s %d\r'%(cmd, value))
+        self._cnx.write('++%s\r'%(cmd))
+        rval = self._read().strip()
+        if not rval.isdigit() or int(rval) != value:
+            raise ConnectionError("Can't set GPIB %s to %s [ret=%s]"%(cmd, value, repr(rval)))