diff --git a/app/src/async_stream.py b/app/src/async_stream.py
index 3676f96..21bb6b9 100644
--- a/app/src/async_stream.py
+++ b/app/src/async_stream.py
@@ -179,10 +179,11 @@ class AsyncStream(AsyncIfcImpl):
         self.proc_start = time.time()
         while True:
             try:
-                proc = time.time() - self.proc_start
-                if proc > self.proc_max:
-                    self.proc_max = proc
-                self.proc_start = None
+                if self.proc_start:
+                    proc = time.time() - self.proc_start
+                    if proc > self.proc_max:
+                        self.proc_max = proc
+                    self.proc_start = None
                 dead_conn_to = self.__timeout()
                 await asyncio.wait_for(self.__async_read(),
                                        dead_conn_to)
diff --git a/app/tests/test_async_stream.py b/app/tests/test_async_stream.py
index 864f2c3..afe0039 100644
--- a/app/tests/test_async_stream.py
+++ b/app/tests/test_async_stream.py
@@ -2,6 +2,7 @@
 import pytest
 import asyncio
 import gc
+import time
 
 from app.src.infos import Infos
 from app.src.inverter_base import InverterBase
@@ -38,6 +39,26 @@ def test_timeout_cb():
         cnt += 1
     assert cnt == 0
 
+def test_health():
+    reader = FakeReader()
+    writer =  FakeWriter()
+    
+    ifc =  AsyncStreamClient(reader, writer, None, None)
+    ifc.proc_start = time.time()
+    assert ifc.healthy()
+    ifc.proc_start = time.time() -10
+    assert not ifc.healthy()
+    ifc.proc_start = None
+    assert ifc.healthy()
+
+    del ifc
+
+    cnt = 0
+    for inv in InverterBase:
+        print(f'InverterBase refs:{gc.get_referrers(inv)}')
+        cnt += 1
+    assert cnt == 0
+
 @pytest.mark.asyncio
 async def test_close_cb():
     assert asyncio.get_running_loop()
@@ -92,6 +113,8 @@ async def test_read():
         ifc.close()  # clears the closed callback
         cnt += 1
     def app_read():
+        nonlocal ifc
+        ifc.proc_start -= 3
         return 0.01  # async wait of 0.01 
     cnt = 0
     ifc =  AsyncStreamClient(reader, writer, None, closed)
@@ -99,6 +122,7 @@ async def test_read():
     ifc.rx_set_cb(app_read)
     await ifc.client_loop('')
     print('End loop')
+    assert ifc.proc_max >= 3
     assert 13 == ifc.rx_len()
     assert cnt == 1
     del ifc
@@ -205,3 +229,64 @@ async def test_create_remote_cb():
         print(f'InverterBase refs:{gc.get_referrers(inv)}')
         cnt += 1
     assert cnt == 0
+
+@pytest.mark.asyncio
+async def test_sw_exception():
+    global test
+    assert asyncio.get_running_loop()
+    reader = FakeReader()
+    reader.test  = FakeReader.RD_TEST_SW_EXCEPT
+    reader.on_recv.set()
+    writer =  FakeWriter()
+    cnt = 0
+    def timeout():
+        return 1
+    def closed():
+        nonlocal cnt
+        nonlocal ifc
+        ifc.close()  # clears the closed callback
+        cnt += 1
+    cnt = 0
+    ifc =  AsyncStreamClient(reader, writer, None, closed)
+    ifc.prot_set_timeout_cb(timeout)
+    await ifc.client_loop('')
+    print('End loop')
+    assert cnt == 1
+    del ifc
+
+    cnt = 0
+    for inv in InverterBase:
+        print(f'InverterBase refs:{gc.get_referrers(inv)}')
+        cnt += 1
+    assert cnt == 0
+
+@pytest.mark.asyncio
+async def test_os_error():
+    global test
+    assert asyncio.get_running_loop()
+    reader = FakeReader()
+    reader.test  = FakeReader.RD_TEST_OS_ERROR
+
+    reader.on_recv.set()
+    writer =  FakeWriter()
+    cnt = 0
+    def timeout():
+        return 1
+    def closed():
+        nonlocal cnt
+        nonlocal ifc
+        ifc.close()  # clears the closed callback
+        cnt += 1
+    cnt = 0
+    ifc =  AsyncStreamClient(reader, writer, None, closed)
+    ifc.prot_set_timeout_cb(timeout)
+    await ifc.client_loop('')
+    print('End loop')
+    assert cnt == 1
+    del ifc
+
+    cnt = 0
+    for inv in InverterBase:
+        print(f'InverterBase refs:{gc.get_referrers(inv)}')
+        cnt += 1
+    assert cnt == 0
diff --git a/app/tests/test_modbus_tcp.py b/app/tests/test_modbus_tcp.py
index 6a33727..a39c2cd 100644
--- a/app/tests/test_modbus_tcp.py
+++ b/app/tests/test_modbus_tcp.py
@@ -75,6 +75,8 @@ class FakeReader():
     RD_TEST_0_BYTES = 1
     RD_TEST_TIMEOUT = 2
     RD_TEST_13_BYTES = 3
+    RD_TEST_SW_EXCEPT = 4
+    RD_TEST_OS_ERROR = 5
 
     def __init__(self):
         self.on_recv =  asyncio.Event()
@@ -91,6 +93,13 @@ class FakeReader():
             return b'test-data-req'
         elif self.test == self.RD_TEST_TIMEOUT:
             raise TimeoutError
+        elif self.test == self.RD_TEST_SW_EXCEPT:
+            self.test = self.RD_TEST_0_BYTES
+            self.unknown_var += 1    
+        elif self.test == self.RD_TEST_OS_ERROR:
+            self.test = self.RD_TEST_0_BYTES
+            raise ConnectionRefusedError
+
     def feed_eof(self):
         return