diff --git a/src/driver_iperl.cc b/src/driver_iperl.cc
index 8bcfee4..a1c1307 100644
--- a/src/driver_iperl.cc
+++ b/src/driver_iperl.cc
@@ -18,79 +18,57 @@
 
 #include"meters_common_implementation.h"
 
-using namespace std;
-
-struct MeterIperl : public virtual MeterCommonImplementation
+namespace
 {
-    MeterIperl(MeterInfo &mi, DriverInfo &di);
+    struct Driver : public virtual MeterCommonImplementation
+    {
+        Driver(MeterInfo &mi, DriverInfo &di);
+    };
 
-private:
+    static bool ok = registerDriver([](DriverInfo&di)
+    {
+        di.setName("iperl");
+        di.setMeterType(MeterType::WaterMeter);
+        di.addLinkMode(LinkMode::T1);
+        di.addDetection(MANUFACTURER_SEN,  0x06,  0x68);
+        di.addDetection(MANUFACTURER_SEN,  0x07,  0x68);
+        di.addDetection(MANUFACTURER_SEN,  0x07,  0x7c);
+        di.setConstructor([](MeterInfo& mi, DriverInfo& di){ return shared_ptr<Meter>(new Driver(mi, di)); });
+    });
 
-    double total_water_consumption_m3_ {};
-    double max_flow_m3h_ {};
-};
+    Driver::Driver(MeterInfo &mi, DriverInfo &di) : MeterCommonImplementation(mi, di)
+    {
+        addNumericFieldWithExtractor(
+            "total",
+            "The total water consumption recorded by this meter.",
+            PrintProperty::JSON | PrintProperty::FIELD | PrintProperty::IMPORTANT,
+            Quantity::Volume,
+            VifScaling::Auto,
+            FieldMatcher::build()
+            .set(MeasurementType::Instantaneous)
+            .set(VIFRange::Volume)
+            );
 
-static bool ok = registerDriver([](DriverInfo&di)
-{
-    di.setName("iperl");
-    di.setMeterType(MeterType::WaterMeter);
-    di.addLinkMode(LinkMode::T1);
-    di.addDetection(MANUFACTURER_SEN,  0x06,  0x68);
-    di.addDetection(MANUFACTURER_SEN,  0x07,  0x68);
-    di.addDetection(MANUFACTURER_SEN,  0x07,  0x7c);
-    di.setConstructor([](MeterInfo& mi, DriverInfo& di){ return shared_ptr<Meter>(new MeterIperl(mi, di)); });
-});
-
-MeterIperl::MeterIperl(MeterInfo &mi, DriverInfo &di) : MeterCommonImplementation(mi, di)
-{
-    setMeterType(MeterType::WaterMeter);
-
-    setExpectedTPLSecurityMode(TPLSecurityMode::AES_CBC_IV);
-
-    addLinkMode(LinkMode::T1);
-
-    // version 0x68
-    // version 0x7c Sensus 640
-
-    addNumericFieldWithExtractor(
-        "total",
-        Quantity::Volume,
-        NoDifVifKey,
-        VifScaling::Auto,
-        MeasurementType::Instantaneous,
-        VIFRange::Volume,
-        StorageNr(0),
-        TariffNr(0),
-        IndexNr(1),
-        PrintProperty::JSON | PrintProperty::FIELD | PrintProperty::IMPORTANT,
-        "The total water consumption recorded by this meter.",
-        SET_FUNC(total_water_consumption_m3_, Unit::M3),
-        GET_FUNC(total_water_consumption_m3_, Unit::M3));
-
-    addNumericFieldWithExtractor(
-        "max_flow",
-        Quantity::Flow,
-        NoDifVifKey,
-        VifScaling::Auto,
-        MeasurementType::Instantaneous,
-        VIFRange::VolumeFlow,
-        StorageNr(0),
-        TariffNr(0),
-        IndexNr(1),
-        PrintProperty::JSON | PrintProperty::FIELD | PrintProperty::IMPORTANT,
-        "The maxium flow recorded during previous period.",
-        SET_FUNC(max_flow_m3h_, Unit::M3H),
-        GET_FUNC(max_flow_m3h_, Unit::M3H));
+        addNumericFieldWithExtractor(
+            "max_flow",
+            "The maxium flow recorded during previous period.",
+            PrintProperty::JSON | PrintProperty::FIELD | PrintProperty::IMPORTANT,
+            Quantity::Flow,
+            VifScaling::Auto,
+            FieldMatcher::build()
+            .set(MeasurementType::Instantaneous)
+            .set(VIFRange::VolumeFlow));
+    }
 }
 
 // Test: MoreWater iperl 12345699 NOKEY
 // Comment: Test iPerl T1 telegram, that after decryption, has 2f2f markers.
-// telegram=|1E44AE4C9956341268077A36001000#2F2F0413181E0000023B00002F2F2F2F|
+// telegram=|1E44AE4C9956341268077A36001000_2F2F0413181E0000023B00002F2F2F2F|
 // {"media":"water","meter":"iperl","name":"MoreWater","id":"12345699","total_m3":7.704,"max_flow_m3h":0,"timestamp":"1111-11-11T11:11:11Z"}
 // |MoreWater;12345699;7.704000;0.000000;1111-11-11 11:11.11
 
 // Test: WaterWater iperl 33225544 NOKEY
 // Comment: Test iPerl T1 telegram not encrypted, which has no 2f2f markers.
-// telegram=|1844AE4C4455223368077A55000000|041389E20100023B0000|
+// telegram=|1844AE4C4455223368077A55000000_041389E20100023B0000|
 // {"media":"water","meter":"iperl","name":"WaterWater","id":"33225544","total_m3":123.529,"max_flow_m3h":0,"timestamp":"1111-11-11T11:11:11Z"}
 // |WaterWater;33225544;123.529000;0.000000;1111-11-11 11:11.11