diff --git a/Documentation/UserManual/SCPI_Examples/libreVNA.py b/Documentation/UserManual/SCPI_Examples/libreVNA.py
index 9c9bee7..dcac991 100755
--- a/Documentation/UserManual/SCPI_Examples/libreVNA.py
+++ b/Documentation/UserManual/SCPI_Examples/libreVNA.py
@@ -1,13 +1,14 @@
+import re
 import socket
 from asyncio import IncompleteReadError  # only import the exception class
 import time
 
 class SocketStreamReader:
-    def __init__(self, sock: socket.socket):
+    def __init__(self, sock: socket.socket, default_timeout=1):
         self._sock = sock
         self._sock.setblocking(0)
         self._recv_buffer = bytearray()
-        self.timeout = 1.0
+        self.default_timeout = default_timeout
 
     def read(self, num_bytes: int = -1) -> bytes:
         raise NotImplementedError
@@ -22,12 +23,14 @@ class SocketStreamReader:
             pos += n
         return bytes(buf)
 
-    def readline(self) -> bytes:
-        return self.readuntil(b"\n")
+    def readline(self, timeout=None) -> bytes:
+        return self.readuntil(b"\n", timeout=timeout)
 
-    def readuntil(self, separator: bytes = b"\n") -> bytes:
+    def readuntil(self, separator: bytes = b"\n", timeout=None) -> bytes:
         if len(separator) != 1:
             raise ValueError("Only separators of length 1 are supported.")
+        if timeout is None:
+            timeout = self.default_timeout
 
         chunk = bytearray(4096)
         start = 0
@@ -35,12 +38,12 @@ class SocketStreamReader:
         bytes_read = self._recv_into(memoryview(buf))
         assert bytes_read == len(buf)
 
-        timeout = time.time() + self.timeout
+        time_limit = time.time() + timeout
         while True:
             idx = buf.find(separator, start)
             if idx != -1:
                 break
-            elif time.time() > timeout:
+            elif time.time() > time_limit:
                 raise Exception("Timed out waiting for response from GUI")
 
             start = len(self._recv_buffer)
@@ -66,31 +69,54 @@ class SocketStreamReader:
         return bytes_read
 
 class libreVNA:
-    def __init__(self, host='localhost', port=19542):
+    def __init__(self, host='localhost', port=19542,
+                 default_check_cmds=True, default_timeout=1):
         self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         try:
             self.sock.connect((host, port))
         except:
             raise Exception("Unable to connect to LibreVNA-GUI. Make sure it is running and the TCP server is enabled.")
-        self.reader = SocketStreamReader(self.sock)
+        self.reader = SocketStreamReader(self.sock,
+                                         default_timeout=default_timeout)
+        self.default_check_cmds = default_check_cmds
 
     def __del__(self):
         self.sock.close()
 
-    def __read_response(self):
-        return self.reader.readline().decode().rstrip()
+    def __read_response(self, timeout=None):
+        return self.reader.readline(timeout=timeout).decode().rstrip()
 
-    def cmd(self, cmd):
+    def cmd(self, cmd, check=None, timeout=None):
         self.sock.sendall(cmd.encode())
         self.sock.send(b"\n")
-        resp = self.__read_response()
-        if len(resp) > 0:
-        	raise Exception("Expected empty response but got "+resp)
+        if check or (check is None and self.default_check_cmds):
+            status = self.get_status(timeout=timeout)
+            if self.get_status() & 0x20:
+                raise Exception("Command Error")
+            if self.get_status() & 0x10:
+                raise Exception("Execution Error")
+            if self.get_status() & 0x08:
+                raise Exception("Device Error")
+            if self.get_status() & 0x04:
+                raise Exception("Query Error")
+            return status
+        else:
+            return None
 
-    def query(self, query):
+    def query(self, query, timeout=None):
         self.sock.sendall(query.encode())
         self.sock.send(b"\n")
-        return self.__read_response()
+        return self.__read_response(timeout=timeout)
+
+    def get_status(self, timeout=None):
+        resp = self.query("*ESR?", timeout=timeout)
+        if not re.match(r'^\d+$', resp):
+            raise Exception("Expected numeric response from *ESR? but got "
+                            f"'{resp}'")
+        status = int(resp)
+        if status < 0 or status > 255:
+            raise Exception(f"*ESR? returned invalid value {status}.")
+        return status
     
     @staticmethod
     def parse_VNA_trace_data(data):
diff --git a/Software/Integrationtests/tests/TestBase.py b/Software/Integrationtests/tests/TestBase.py
index 21edf90..983bd53 100644
--- a/Software/Integrationtests/tests/TestBase.py
+++ b/Software/Integrationtests/tests/TestBase.py
@@ -25,7 +25,7 @@ class TestBase(unittest.TestCase):
         
         self.vna = libreVNA('localhost', 19544)
         try:
-            self.vna.cmd(":DEV:CONN")
+            self.vna.cmd("*CLS;:DEV:CONN")
         except Exception as e:
             self.tearDown()
             raise e
diff --git a/Software/Integrationtests/tests/TestCalibration.py b/Software/Integrationtests/tests/TestCalibration.py
index 234613f..5fb7a14 100644
--- a/Software/Integrationtests/tests/TestCalibration.py
+++ b/Software/Integrationtests/tests/TestCalibration.py
@@ -7,11 +7,9 @@ class TestCalibration(TestBase):
     def cal_measure(self, number, timeout = 3):
         self.vna.cmd(":VNA:CAL:MEAS "+str(number))
         # wait for the measurement to finish
-        stoptime = time.time() + timeout
-        while self.vna.query(":VNA:CAL:BUSY?") == "TRUE":
-            if time.time() > stoptime:
-                raise AssertionError("Calibration measurement timed out")
-            time.sleep(0.1)
+        assert self.vna.query(":VNA:CAL:BUSY?") == "TRUE"
+        self.vna.cmd("*WAI")
+        assert self.vna.query(":VNA:CAL:BUSY?") == "FALSE"
     
     def test_dummy_calibration(self):
         # This test just iterates through the calibration steps. As no actual standards
@@ -29,7 +27,8 @@ class TestCalibration(TestBase):
         self.vna.cmd(":VNA:CAL:RESET")
 
         # No measurements yet, activating should fail
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_1"), "ERROR")
+        self.vna.cmd(":VNA:CAL:ACT SOLT_1", check=False)
+        self.assertTrue(self.vna.get_status() & 0x3C)
 
         # Load calibration kit
         self.assertEqual(self.vna.query(":VNA:CAL:KIT:LOAD? DUMMY.CALKIT"), "TRUE")
@@ -47,11 +46,14 @@ class TestCalibration(TestBase):
         self.cal_measure(2)
                            
         # SOLT_1 should now be available
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_1"), "")
+        self.vna.cmd(":VNA:CAL:ACT SOLT_1", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
 
         # SOLT_2 and SOLT_12 should still be unavailable
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_2"), "ERROR")
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_12"), "ERROR")
+        self.vna.cmd(":VNA:CAL:ACT SOLT_2", check=False)
+        self.assertTrue(self.vna.get_status() & 0x3C)
+        self.vna.cmd(":VNA:CAL:ACT SOLT_12", check=False)
+        self.assertTrue(self.vna.get_status() & 0x3C)
 
         # Take measurements for SOLT_2
         self.vna.cmd(":VNA:CAL:ADD OPEN")
@@ -66,11 +68,14 @@ class TestCalibration(TestBase):
         self.cal_measure(5)
 
         # SOLT_1 and SOLT_2 should now be available
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_1"), "")
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_2"), "")
-        
+        self.vna.cmd(":VNA:CAL:ACT SOLT_1", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
+        self.vna.cmd(":VNA:CAL:ACT SOLT_2", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
+
         # SOLT_12 should still be unavailable
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_12"), "ERROR")
+        self.vna.cmd(":VNA:CAL:ACT SOLT_12", check=False)
+        self.assertTrue(self.vna.get_status() & 0x3C)
 
         # Take the final through measurement for SOLT_12
         self.vna.cmd(":VNA:CAL:ADD THROUGH")
@@ -79,9 +84,12 @@ class TestCalibration(TestBase):
         self.cal_measure(6)
         
         # SOLT_1, SOLT_2 and SOLT_12 should now be available
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_1"), "")
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_2"), "")
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_12"), "")
+        self.vna.cmd(":VNA:CAL:ACT SOLT_1", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
+        self.vna.cmd(":VNA:CAL:ACT SOLT_2", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
+        self.vna.cmd(":VNA:CAL:ACT SOLT_12", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
         
     def assertTrace_dB(self, trace, dB_nominal, dB_deviation):
         for S in trace:
@@ -135,7 +143,8 @@ class TestCalibration(TestBase):
         self.cal_measure(6, 15)
         
         # activate calibration
-        self.assertEqual(self.vna.query(":VNA:CAL:ACT SOLT_12"), "")
+        self.vna.cmd(":VNA:CAL:ACT SOLT_12", check=False)
+        self.assertFalse(self.vna.get_status() & 0x3C)
 
         # switch in 6dB attenuator
         cal.setPort(cal.Standard.THROUGH, 1, 2)        
@@ -143,8 +152,9 @@ class TestCalibration(TestBase):
 
         # Start measurement and grab data
         self.vna.cmd(":VNA:ACQ:SINGLE TRUE")
-        while self.vna.query(":VNA:ACQ:FIN?") == "FALSE":
-            time.sleep(0.1)
+        self.assertEqual(self.vna.query(":VNA:ACQ:FIN?") == "FALSE")
+        self.vna.cmd("*WAI")
+        self.assertEqual(self.vna.query(":VNA:ACQ:FIN?") == "TRUE")
 
         cal.reset()
         
@@ -162,5 +172,4 @@ class TestCalibration(TestBase):
         # Reflection should be below -10dB (much lower for most frequencies)
         self.assertTrace_dB(S11, -100, 90)
         self.assertTrace_dB(S22, -100, 90)
-        
-        
\ No newline at end of file
+
diff --git a/Software/Integrationtests/tests/TestVNASweep.py b/Software/Integrationtests/tests/TestVNASweep.py
index bae3143..3e0a87d 100644
--- a/Software/Integrationtests/tests/TestVNASweep.py
+++ b/Software/Integrationtests/tests/TestVNASweep.py
@@ -4,11 +4,9 @@ import time
 class TestVNASweep(TestBase):
     def waitSweepTimeout(self, timeout = 1):
         self.assertEqual(self.vna.query(":VNA:ACQ:FIN?"), "FALSE")
-        stoptime = time.time() + timeout
-        while self.vna.query(":VNA:ACQ:FIN?") == "FALSE":
-            if time.time() > stoptime:
-                raise AssertionError("Sweep timed out")
-            
+        self.vna.cmd("*WAI", timeout=timeout)
+        self.assertEqual(self.vna.query(":VNA:ACQ:FIN?"), "TRUE")
+
     def test_sweep_frequency(self):
         self.vna.cmd(":DEV:MODE VNA")
         self.vna.cmd(":VNA:SWEEP FREQUENCY")