fix

rfg_vna_viewer.py

@@ -53,10 +53,16 @@ class DataReader:
         os.set_blocking(self._fd, False)
 
     def read_available(self):
-        try:
-            return os.read(self._fd, READ_CHUNK)
-        except BlockingIOError:
-            return b""
+        chunks = []
+        while True:
+            try:
+                data = os.read(self._fd, READ_CHUNK)
+                if not data:
+                    break
+                chunks.append(data)
+            except BlockingIOError:
+                break
+        return b"".join(chunks)
 
     def close(self):
         os.close(self._fd)