diff --git a/provider/modbus.go b/provider/modbus.go
index e85b4b158..a50a26246 100644
--- a/provider/modbus.go
+++ b/provider/modbus.go
@@ -10,6 +10,7 @@ import (
 	"github.com/volkszaehler/mbmd/meters/sunspec"
 )
 
+// Modbus implements modbus RTU and TCP access
 type Modbus struct {
 	log     *api.Logger
 	conn    meters.Connection
@@ -130,7 +131,9 @@ func (m *Modbus) FloatGetter() (float64, error) {
 		res, err = dev.QueryOp(m.conn.ModbusClient(), m.op.IEC61850)
 	}
 
-	m.log.TRACE.Printf("%+v", res)
+	if err == nil {
+		m.log.TRACE.Printf("%+v", res)
+	}
 
 	return res.Value, err
 }