diff --git a/src/r2x/exporter/plexos.py b/src/r2x/exporter/plexos.py
index ae2c09a0..fdfd2a62 100644
--- a/src/r2x/exporter/plexos.py
+++ b/src/r2x/exporter/plexos.py
@@ -41,6 +41,7 @@
     Transformer2W,
     TransmissionInterface,
 )
+from r2x.models.branch import Line
 from r2x.units import get_magnitude
 from r2x.utils import custom_attrgetter, get_enum_from_string, read_json
 
@@ -211,6 +212,8 @@ def insert_component_properties(
         match component_type.__name__:
             case "GenericBattery":
                 custom_map = {"active_power": "Max Power", "storage_capacity": "Capacity"}
+            case "Line":
+                custom_map = {"rating": "Max Flow"}
             case _:
                 custom_map = {}
         property_map = self.property_map | custom_map
@@ -247,7 +250,9 @@ def add_component_category(
         class_id = self._db_mgr.get_class_id(class_enum)
         categories = [
             (class_id, rank, category or "")
-            for rank, category in enumerate(sorted(component_categories), start=existing_rank + 1)
+            for rank, category in enumerate(
+                sorted(component_categories, key=lambda x: (x is None, x)), start=existing_rank + 1
+            )
         ]
 
         # Maybe replace `t_category` with right schema.
@@ -415,6 +420,8 @@ def add_lines(self) -> None:
         # NOTE: The default line on Plexos is a `MonitoredLine` without category. If we need to add a category
         # in the future, we will uncomment the line below with the pertinent category name.
         # self.add_component_category(MonitoredLine, class_enum=ClassEnum.Line)
+        self.bulk_insert_objects(Line, class_enum=ClassEnum.Line, collection_enum=CollectionEnum.Lines)
+        self.insert_component_properties(Line, parent_class=ClassEnum.System, collection=CollectionEnum.Lines)
         self.bulk_insert_objects(
             MonitoredLine, class_enum=ClassEnum.Line, collection_enum=CollectionEnum.Lines
         )
@@ -426,7 +433,7 @@ def add_lines(self) -> None:
         collection_properties = self._db_mgr.get_valid_properties(
             collection=CollectionEnum.Lines, parent_class=ClassEnum.System, child_class=ClassEnum.Line
         )
-        for line in self.system.get_components(MonitoredLine, filter_func=lambda x: getattr(x, "ext", False)):
+        for line in self.system.get_components(MonitoredLine, Line):
             properties = get_export_properties(
                 line.ext,
                 partial(apply_property_map, property_map=self.property_map),
diff --git a/src/r2x/models/costs.py b/src/r2x/models/costs.py
index 40e4f5e2..83b13e2a 100644
--- a/src/r2x/models/costs.py
+++ b/src/r2x/models/costs.py
@@ -2,8 +2,9 @@
 
 from typing import Annotated
 from infrasys.models import InfraSysBaseModelWithIdentifers
+from infrasys.value_curves import LinearCurve
 from pydantic import Field, computed_field
-from infrasys.cost_curves import ProductionVariableCostCurve
+from infrasys.cost_curves import FuelCurve, ProductionVariableCostCurve
 from r2x.units import Currency, FuelPrice
 from operator import attrgetter
 
@@ -59,6 +60,15 @@ class ThermalGenerationCost(OperationalCost):
     start_up: Annotated[Currency | None, Field(description="Cost to start the unit.")] = Currency(0, "usd")
     variable: ProductionVariableCostCurve | None = None
 
+    @classmethod
+    def example(cls) -> "ThermalGenerationCost":
+        return ThermalGenerationCost(
+            fixed=FuelPrice(0, "usd/MWh"),
+            shut_down=Currency(100, "usd"),
+            start_up=Currency(100, "usd"),
+            variable=FuelCurve(value_curve=LinearCurve(10)),  # type: ignore
+        )
+
 
 class StorageCost(OperationalCost):
     charge_variable_cost: ProductionVariableCostCurve | None = None
diff --git a/src/r2x/parser/parser_helpers.py b/src/r2x/parser/parser_helpers.py
index b7d4bc59..4fbb9e4a 100644
--- a/src/r2x/parser/parser_helpers.py
+++ b/src/r2x/parser/parser_helpers.py
@@ -144,10 +144,10 @@ def fill_missing_timestamps(data_file: pl.DataFrame, hourly_time_index: pl.DataF
     ... ).to_frame("datetime")
     >>> fill_missing_timestamps(df, hourly_time_index)
     """
-    # Match case based on available columns
-    match data_file.columns:
+    column_set = set(data_file.columns)
+    match column_set:
         # Case when "year", "month", "day", and "hour" are all present
-        case ["year", "month", "day", "hour", *_]:
+        case s if s.issuperset({"year", "month", "day", "hour"}):
             data_file = data_file.with_columns(
                 pl.datetime(pl.col("year"), pl.col("month"), pl.col("day"), pl.col("hour"))
             )
@@ -155,13 +155,13 @@ def fill_missing_timestamps(data_file: pl.DataFrame, hourly_time_index: pl.DataF
             return upsample_data.fill_null(strategy="forward")
 
         # Case when "year", "month", and "day" are present but "hour" is missing
-        case ["year", "month", "day", *_]:
+        case s if s.issuperset({"year", "month", "day"}):
             data_file = data_file.with_columns(pl.datetime(pl.col("year"), pl.col("month"), pl.col("day")))
             upsample_data = hourly_time_index.join(data_file, on="datetime", how="left")
             return upsample_data.fill_null(strategy="forward")
 
         # Case when "day" is missing, but "year" and "month" are present
-        case ["year", "month", *_] if "day" not in data_file.columns:
+        case s if s.issuperset({"year", "month"}):
             data_file = data_file.with_columns(pl.datetime(pl.col("year"), pl.col("month"), 1))  # First day
             upsample_data = hourly_time_index.join(data_file, on="datetime", how="left")
             return upsample_data.fill_null(strategy="forward")
@@ -200,16 +200,20 @@ def resample_data_to_hourly(data_file: pl.DataFrame) -> pl.DataFrame:
     # Expecting two rows: one for hour 0 and one for hour 1
     """
     # Create a timestamp from year, month, day, hour, and minute
+    if max(data_file["period"]) == 48.0:  # sub-hourly data
+        data_file = data_file.with_columns(((pl.col("period") - 1) / 2).cast(pl.Int32).alias("hour"))
     data_file = data_file.with_columns(
         pl.datetime(
             data_file["year"],
             data_file["month"],
             data_file["day"],
             hour=data_file["hour"],
-            minute=data_file["minute"],
+            # minute=data_file["minute"],
         ).alias("timestamp")
     )
 
+    data_file = data_file.drop_nulls().sort("timestamp")
+
     # Group by the hour and aggregate the values
     return (
         data_file.group_by_dynamic("timestamp", every="1h")
diff --git a/src/r2x/parser/plexos.py b/src/r2x/parser/plexos.py
index f1a51b6a..c328d643 100644
--- a/src/r2x/parser/plexos.py
+++ b/src/r2x/parser/plexos.py
@@ -167,7 +167,12 @@ def __init__(self, *args, xml_file: str | None = None, **kwargs) -> None:
         # TODO(pesap): Rename exceptions to include R2X
         # https://github.com/NREL/R2X/issues/5
         # R2X needs at least one of this maps defined to correctly work.
-        if not self.fuel_map and not self.device_map and not self.device_match_string:
+        if (
+            not self.fuel_map
+            and not self.device_map
+            and not self.device_match_string
+            and not self.category_map
+        ):
             msg = (
                 "Neither `plexos_fuel_map` or `plexos_device_map` or `device_match_string` was provided. "
                 "To fix, provide any of the mappings."
@@ -858,7 +863,7 @@ def _construct_value_curves(self, record, generator_name):  # noqa: C901
         heat_rate_avg = (
             Quantity(
                 np.median(heat_rate_avg.data),
-                units=heat_rate_avg.units,
+                units=heat_rate_avg.data.units,
             )
             if isinstance(heat_rate_avg, SingleTimeSeries)
             else heat_rate_avg
@@ -866,7 +871,7 @@ def _construct_value_curves(self, record, generator_name):  # noqa: C901
         heat_rate_base = (
             Quantity(
                 np.median(heat_rate_base.data),
-                units=heat_rate_base.units,
+                units=heat_rate_base.data.units,
             )
             if isinstance(heat_rate_base, SingleTimeSeries)
             else heat_rate_base
@@ -874,7 +879,7 @@ def _construct_value_curves(self, record, generator_name):  # noqa: C901
         heat_rate_incr = (
             Quantity(
                 np.median(heat_rate_incr.data),
-                units=heat_rate_incr.units,
+                units=heat_rate_incr.data.units,
             )
             if isinstance(heat_rate_incr, SingleTimeSeries)
             else heat_rate_incr
@@ -1091,7 +1096,7 @@ def _set_unit_capacity(self, record):
         if rating_factor := record.get("Rating Factor"):
             if isinstance(rating_factor, SingleTimeSeries):
                 rating_factor_data = rating_factor.data
-                if rating_factor.units == "percent":
+                if rating_factor_data.units == "percent":
                     rating_factor_data = rating_factor_data.to("")
                 if not (max_active_power := record.get("max_active_power")):
                     # Order of the operation matters
@@ -1195,7 +1200,7 @@ def _construct_load_profiles(self):
 
             if max_active_power := mapped_records.get("max_active_power"):
                 max_load = (
-                    np.max(max_active_power.data)
+                    np.nanmax(max_active_power.data)
                     if isinstance(max_active_power, SingleTimeSeries)
                     else max_active_power
                 )
diff --git a/src/r2x/parser/plexos_utils.py b/src/r2x/parser/plexos_utils.py
index f90d0fdf..6306c758 100644
--- a/src/r2x/parser/plexos_utils.py
+++ b/src/r2x/parser/plexos_utils.py
@@ -26,7 +26,7 @@ class DATAFILE_COLUMNS(Enum):  # noqa: N801
     """Enum of possible Data file columns in Plexos."""
 
     NV = ("name", "value")
-    Y = "year"
+    Y = ("year",)
     PV = ("pattern", "value")
     TS_NPV = ("name", "pattern", "value")
     TS_NYV = ("name", "year", "value")
diff --git a/tests/models/pjm.py b/tests/models/pjm.py
index ae6b4fee..ef6a2d30 100644
--- a/tests/models/pjm.py
+++ b/tests/models/pjm.py
@@ -30,7 +30,8 @@ def pjm_2area() -> System:
     # Add topology elements
     system.add_component(Area(name="init"))
     system.add_component(Area(name="Area2"))
-    system.add_component(LoadZone(name="LoadZone1"))
+    system.add_component(LoadZone(name="init"))
+    system.add_component(LoadZone(name="Area2"))
 
     for bus in pjm_2area_components["bus"]:
         system.add_component(
@@ -40,6 +41,7 @@ def pjm_2area() -> System:
                 bus_type=ACBusTypes(bus["bustype"]),
                 base_voltage=Voltage(bus["base_voltage"], "kV"),
                 area=system.get_component(Area, bus["area"]),
+                load_zone=system.get_component(LoadZone, bus["area"]),
                 magnitude=bus["magnitude"],
             )
         )
@@ -68,7 +70,7 @@ def pjm_2area() -> System:
         x=0.03,
         to_bus=bust,
         rating_up=1000 * ureg.MW,
-        rating=1000 * ureg.MW,
+        rating_down=-1000 * ureg.MW,
     )
     system.add_component(branch_monitored)
 
@@ -97,14 +99,15 @@ def pjm_2area() -> System:
                 startup_cost=gen["StartupCost"] * ureg.Unit("usd"),
                 shutdown_cost=gen["ShutDnCost"] * ureg.Unit("usd"),
                 vom_price=gen["VOM"] * ureg.Unit("usd/MWh"),
-                min_down_time=gen["MinTimeDn"],
-                min_up_time=gen["MinTimeUp"],
+                min_down_time=Time(gen["MinTimeDn"], "hour"),
+                min_up_time=Time(gen["MinTimeUp"], "hour"),
                 mean_time_to_repair=Time(10.0, "hour"),
                 forced_outage_rate=Percentage(0.0),
                 planned_outage_rate=Percentage(0.0),
                 ramp_up=gen["RampLimitsUp"],
                 ramp_down=gen["RampLimitsDn"],
                 bus=system.get_component(ACBus, gen["BusName"]),
+                category="thermal",
             )
         )
 
@@ -169,7 +172,7 @@ def pjm_2area() -> System:
     reserve_map = ReserveMap(name="pjm_reserve_map")
     reserve = Reserve(
         name="SpinUp-pjm",
-        region=system.get_component(LoadZone, "LoadZone1"),
+        region=system.get_component(LoadZone, "init"),
         reserve_type=ReserveType.SPINNING,
         vors=0.05,
         duration=3600.0,
diff --git a/tests/test_parser_helper.py b/tests/test_parser_helper.py
index 20d3b56a..57a59638 100644
--- a/tests/test_parser_helper.py
+++ b/tests/test_parser_helper.py
@@ -146,6 +146,9 @@ def test_fill_missing_timestamps():
     # Assert that the result contains 24 rows (for each hour of the day)
     assert len(result) == 24
 
+    data_file = pl.DataFrame({"name": ["testname"], "year": [2020], "month": [1], "value": [1]})
+    result = fill_missing_timestamps(data_file, hourly_time_index)
+
     data_file = pl.DataFrame({"year": [2020], "value": [1]})
     with pytest.raises(ValueError):
         _ = fill_missing_timestamps(data_file, hourly_time_index)
diff --git a/tests/test_plexos_utils.py b/tests/test_plexos_utils.py
index 7ec5276d..b4bec79a 100644
--- a/tests/test_plexos_utils.py
+++ b/tests/test_plexos_utils.py
@@ -6,7 +6,9 @@
 
 def test_get_column_enum():
     """Test multiple cases for get_column_enum function."""
-    # Case 1: Exact match for NV
+    columns = ["year", "random_column", "random_column_2"]
+    assert get_column_enum(columns) == DATAFILE_COLUMNS.Y
+
     columns = ["name", "value"]
     assert get_column_enum(columns) == DATAFILE_COLUMNS.NV