diff --git a/include/adclib/adclib_device1.h b/include/adclib/adclib_device1.h
index dd379b1..19496f8 100644
--- a/include/adclib/adclib_device1.h
+++ b/include/adclib/adclib_device1.h
@@ -226,6 +226,40 @@ protected:
     snplib::HeterogenMap<ATTR_ID_T> _attrGetter{};
     snplib::HeterogenMap<ATTR_ID_T> _attrSetter{};
 
+
+    template <typename GT, typename UGT>
+        requires requires(std::invoke_result_t<GT> v, std::invoke_result_t<UGT> u) { u = v; }
+    inline static auto default_cnv_from_func = [](GT const& g) -> adc_result_t<UGT> {
+        using u_t = std::invoke_result_t<UGT>;
+
+        return [g]() -> adc_result_t<u_t> {
+            auto v = g();
+
+            if (v) {
+                return static_cast<u_t>(v.value());
+            }
+
+            return v.error();
+        };
+    };
+
+
+    template <typename GT, typename UGT>
+        requires requires(std::invoke_result_t<GT> v, std::invoke_result_t<UGT> u) { v = u; }
+    inline static auto default_cnv_to_func = [](UGT const& g) -> adc_result_t<GT> {
+        using v_t = std::invoke_result_t<GT>;
+
+        return [g]() -> adc_result_t<v_t> {
+            auto v = g();
+
+            if (v) {
+                return static_cast<v_t>(v.value());
+            }
+
+            return v.error();
+        };
+    };
+
 public:
     static constexpr std::tuple<bool,
                                 char,
@@ -270,8 +304,8 @@ public:
         _commands.emplace(std::move(id), std::forward<ET>(exec_func));
     }
 
-    template <typename GT, typename ST, typename... VTs>
-    void addAttr(ATTR_ID_T id, GT&& getter, ST&& setter, std::tuple<VTs...> = std::tuple<>{})
+    template <typename GT, typename ST, typename... UTs>
+    void addAttr(ATTR_ID_T id, GT&& getter, ST&& setter, std::tuple<UTs...> = std::tuple<>{})
     {
         using v_t = adclib_attr_value_deduced_t<GT, ST>;
         static_assert(!std::is_void_v<v_t>, "Getter and setter cannot be nullptr_t at the same time!");
@@ -281,12 +315,15 @@ public:
         }
 
         _attrGetter.push(id, attr_getter_t<std::remove_cvref_t<GT>>(std::forward<GT>(getter)),
-                         std::tuple<attr_getter_t<VTs>...>{});
+                         std::tuple<attr_getter_t<UTs>...>{});
 
         _attrSetter.push(id, attr_setter_t<std::remove_cvref_t<ST>>(std::forward<ST>(setter)),
-                         std::tuple<attr_setter_t<VTs>...>{});
+                         std::tuple<attr_setter_t<UTs>...>{});
     }
 
+    //
+    // conversional functions are the same as defined in the snplib::hmap class
+    // (it must convert attribute values instead of getters or setters itself!)
     template <adclib_attr_getter_c GT, adclib_attr_setter_c ST, typename... FuncTs>
         requires(sizeof...(FuncTs) > 1)
     void addAttr(ATTR_ID_T id, GT&& getter, ST&& setter, FuncTs&&... cnv_pairs)
@@ -297,6 +334,48 @@ public:
 
         using v_t = adclib_attr_value_deduced_t<GT, ST>;
         static_assert(!std::is_void_v<v_t>, "Getter and setter cannot be nullptr_t at the same time!");
+
+        [... cnv_pairs_cap = std::forward<FuncTs>(cnv_pairs), id, getter_cap = std::forward<GT>(getter),
+         setter_cap = std::forward<ST>(setter), this]<size_t... Is>(std::index_sequence<Is...>) mutable {
+            auto tp = std::forward_as_tuple(std::forward<FuncTs>(cnv_pairs_cap)...);
+
+            auto gt_cnv_from_func = []<size_t I, snplib::snplib_tuple_c TpT>(TpT const& tpl) {
+                using u_t = std::tuple_element_t<I, TpT>::value_type;
+
+                static_assert(requires(v_t v, u_t u) { u = v; }, "Invalid deduced user type!");
+
+                return [&tpl](attr_getter_t<v_t> const& gt) -> adc_result_t<attr_getter_t<u_t>> {
+                    return [&tpl, &gt]() -> adc_result_t<u_t> {
+                        auto v = gt();
+                        if (v) {
+                            // convert from inner type to user's ("convert-from" function)
+                            // it returns adc_result_t<u_t>
+                            return std::forward<std::tuple_element_t<I, TpT>>(std::get<I>(tpl))(v.value());
+                        }
+
+                        return std::unexpected(v.error());
+                    };
+                };
+            };
+
+            auto st_cnv_from_func = []<size_t I, snplib::snplib_tuple_c TpT>(TpT const& tpl) {
+                using u_t = std::tuple_element_t<I, TpT>::value_type;
+
+                static_assert(requires(v_t v, u_t u) { u = v; }, "Invalid deduced user type!");
+
+                return [&tpl](attr_setter_t<v_t> const& st) -> adc_result_t<attr_setter_t<u_t>> {
+                    return [&tpl, &st](u_t const& uval) -> adc_error_t {
+                        // convert from user type to inner ("convert-to" function)!
+                        auto val = std::forward<std::tuple_element_t<I + 1, TpT>>(std::get<I + 1>(tpl))(uval);
+                        if (val) {
+                            return st(val.value());
+                        }
+
+                        return std::unexpected(val.error());
+                    };
+                };
+            };
+        }(std::make_index_sequence<NFUNCS / 2>{});
     }
 };