Remove cache of hpib_address

hpib.py

@@ -19,7 +19,6 @@ class PortDevice(object):
 
 class PrologixGpibUsb(PortDevice):
     _serialPort = None
-    _hpib_address = -1
     _devices = "Not scanned."
 
     def __init__(self, port="", timeout=1, port_format="%d", max_device_num=9, verbose=False,
@@ -99,17 +98,13 @@ class PrologixGpibUsb(PortDevice):
                 self._devices += [address, returnStr]
 
     def command(self, hpib_address, command):
-        if hpib_address != self._hpib_address:
-            command = "++addr " + str(hpib_address) + chr(10) + command
-            self._hpib_address = hpib_address
+        command = "++addr " + str(hpib_address) + chr(10) + command
 
         with self._lock:
             self._write_serial(command + chr(10))
 
     def query(self, hpib_address, query, count=80):
-        if hpib_address != self._hpib_address:
-            query = "++addr " + str(hpib_address) + chr(10) + query
-            self._hpib_address = hpib_address
+        query = "++addr " + str(hpib_address) + chr(10) + query
 
         query += chr(10) + "++read eoi" + chr(10)
         with self._lock: