fix(io): Handle large integer values with fallback to raw byte arrays

Added a fallback mechanism to handle cases where integer values exceed
valid range by using raw byte arrays (`ay`). Updated D-Bus methods and
properties to support this behavior.

Signed-off-by: Sven Sager <s.sager@kunbus.com>

src/revpi_middleware/ios1/interface_ios.py

@@ -2,6 +2,7 @@
 # SPDX-FileCopyrightText: 2025 KUNBUS GmbH
 # SPDX-License-Identifier: GPL-2.0-or-later
 """D-Bus interfaces for IOs."""
+
 from typing import Union
 
 from dbus import SystemBus, SessionBus
@@ -34,15 +35,26 @@ class InterfaceInput:
     PropertiesChanged = signal()
 
     def __init__(self, dbus: Union[SystemBus, SessionBus], io: IOBase):
+        self._raw = False
         self.dbus = dbus
         self.io = io
-        self.variant_type = get_variant_type(self.io)
+        try:
+            self.variant_type = get_variant_type(self.io)
+        except ValueError:
+            # Fallback to bytes if the integer is too large
+            self._raw = True
+            self.variant_type = "ay"
 
     def emit_io_change(self):
         if self.interface_name:
             self.PropertiesChanged(
                 self.interface_name,
-                {"value": Variant(self.variant_type, self.io.value)},
+                {
+                    "value": Variant(
+                        self.variant_type,
+                        self.io.get_value() if self._raw else self.io.value,
+                    ),
+                },
                 [],
             )
 
@@ -70,7 +82,10 @@ class InterfaceInput:
 
     @property
     def defaultvalue(self) -> Variant:
-        return Variant(self.variant_type, self.io.defaultvalue)
+        return Variant(
+            self.variant_type,
+            self.io.get_value() if self._raw else self.io.defaultvalue,
+        )
 
     @property
     def length(self) -> int:
@@ -95,7 +110,10 @@ class InterfaceInput:
 
     @property
     def value(self) -> Variant:
-        return Variant(self.variant_type, self.io.value)
+        return Variant(
+            self.variant_type,
+            self.io.get_value() if self._raw else self.io.value,
+        )
 
 
 class InterfaceOutput(InterfaceInput):
@@ -123,7 +141,10 @@ class InterfaceOutput(InterfaceInput):
 
     @value.setter
     def value(self, value: Variant) -> None:
-        self.io.value = value
+        if self._raw:
+            self.io.set_value(value)
+        else:
+            self.io.value = value
         self.io._parentdevice._modio.writeprocimg()