Fix: ip instrument log empty responce and ensure all data is send (#719)

jenshnielsen · WilliamHPNielsen · commit e4a22f984c3f · 2017-09-19T11:14:28.000+02:00
* Fix: ip instrument log empty responce As I understand it that is a sign of a closed socket This should probably be an error in the future * Use sendall fixes #748
diff --git a/qcodes/instrument/ip.py b/qcodes/instrument/ip.py
@@ -1,8 +1,10 @@
 """Ethernet instrument driver class based on sockets."""
 import socket
+import logging
 
 from .base import Instrument
 
+log = logging.getLogger(__name__)
 
 class IPInstrument(Instrument):
 
@@ -139,10 +141,14 @@ def set_terminator(self, terminator):
 
     def _send(self, cmd):
         data = cmd + self._terminator
-        self._socket.send(data.encode())
+        self._socket.sendall(data.encode())
 
     def _recv(self):
-        return self._socket.recv(self._buffer_size).decode()
+        result = self._socket.recv(self._buffer_size)
+        if result == b'':
+            log.warning("Got empty response from Socket recv() "
+                        "Connection broken.")
+        return result.decode()
 
     def close(self):
         """Disconnect and irreversibly tear down the instrument."""
