diff --git a/meters/rs485/orno1p504.go b/meters/rs485/orno1p504.go
index 57ed105f..b1ccd83d 100644
--- a/meters/rs485/orno1p504.go
+++ b/meters/rs485/orno1p504.go
@@ -6,26 +6,25 @@ func init() {
 	Register("ORNO1P504", NewORNO1P504Producer)
 }
 
-var ops1p504 Opcodes = Opcodes{
-
-	Frequency:     0x02, // 16 bit, Hz
-	Voltage:       0x00, // 16 bit, V
-	Current:       0x01, // 16 bit, A
-	Power:         0x03, // 16 bit, W
-	ReactivePower: 0x04, // 16 bit, var
-	ApparentPower: 0x05, // 16 bit, va
-	Cosphi:        0x06, // 16 bit,
-
-	Sum:         0x07, //32 Bit, wh
-	ReactiveSum: 0x09, //32 Bit, varh
-}
-
 type ORNO1P504Producer struct {
 	Opcodes
 }
 
 func NewORNO1P504Producer() Producer {
-	return &ORNO1P504Producer{Opcodes: ops1p504}
+	ops := Opcodes{
+		Frequency:     0x02, // 16 bit, Hz
+		Voltage:       0x00, // 16 bit, V
+		Current:       0x01, // 16 bit, A
+		Power:         0x03, // 16 bit, W
+		ReactivePower: 0x04, // 16 bit, var
+		ApparentPower: 0x05, // 16 bit, va
+		Cosphi:        0x06, // 16 bit,
+
+		Sum:         0x07, // 32 Bit, wh
+		ReactiveSum: 0x09, // 32 Bit, varh
+	}
+
+	return &ORNO1P504Producer{Opcodes: ops}
 }
 
 // Description implements Producer interface
diff --git a/meters/rs485/producer.go b/meters/rs485/producer.go
index 1539ea2c..6c3845d9 100644
--- a/meters/rs485/producer.go
+++ b/meters/rs485/producer.go
@@ -2,6 +2,8 @@ package rs485
 
 import (
 	"fmt"
+	"maps"
+	"slices"
 
 	"github.com/volkszaehler/mbmd/meters"
 )
@@ -21,6 +23,9 @@ type Producer interface {
 	// Type returns device description, typically static
 	Description() string
 
+	// Measurements returns the defined device readings
+	Measurements() []meters.Measurement
+
 	// Produce creates a slice of possible device operations
 	Produce() []Operation
 
@@ -33,10 +38,14 @@ type Producer interface {
 type Opcodes map[meters.Measurement]uint16
 
 // Opcode returns physical register for measurement type
-func (o *Opcodes) Opcode(iec meters.Measurement) uint16 {
-	if opcode, ok := (*o)[iec]; ok {
+func (o Opcodes) Opcode(iec meters.Measurement) uint16 {
+	if opcode, ok := (o)[iec]; ok {
 		return opcode
 	}
 
 	panic(fmt.Sprintf("Undefined opcode for measurement %s", iec.String()))
 }
+
+func (o Opcodes) Measurements() []meters.Measurement {
+	return slices.Collect(maps.Keys(o))
+}
diff --git a/meters/rs485/producer_test.go b/meters/rs485/producer_test.go
new file mode 100644
index 00000000..aff3a678
--- /dev/null
+++ b/meters/rs485/producer_test.go
@@ -0,0 +1,14 @@
+package rs485
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestProducers(t *testing.T) {
+	for name, fun := range Producers {
+		p := fun()
+		assert.Equal(t, len(p.Measurements()), len(p.Produce()), name)
+	}
+}