From c31ba94bb859eb451e02f674eeaf5bfac722f9eb Mon Sep 17 00:00:00 2001
From: Steven Soroka <ssoroka@influxdata.com>
Date: Tue, 10 Mar 2020 16:46:36 -0400
Subject: [PATCH] modbus to support scaling int32 and float32-ieee (#7148)

---
 plugins/inputs/modbus/modbus.go      | 25 ++++++++++++++++---------
 plugins/inputs/modbus/modbus_test.go | 20 ++++++++++++++++++++
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/plugins/inputs/modbus/modbus.go b/plugins/inputs/modbus/modbus.go
index d2e913039..e96b2f117 100644
--- a/plugins/inputs/modbus/modbus.go
+++ b/plugins/inputs/modbus/modbus.go
@@ -468,27 +468,26 @@ func convertDataType(t fieldContainer, bytes []byte) interface{} {
 	switch t.DataType {
 	case "UINT16":
 		e16 := convertEndianness16(t.ByteOrder, bytes)
-		f16 := format16(t.DataType, e16).(uint16)
-		return scaleUint16(t.Scale, f16)
+		return scaleUint16(t.Scale, e16)
 	case "INT16":
 		e16 := convertEndianness16(t.ByteOrder, bytes)
-		f16 := format16(t.DataType, e16).(int16)
+		f16 := int16(e16)
 		return scaleInt16(t.Scale, f16)
 	case "UINT32":
 		e32 := convertEndianness32(t.ByteOrder, bytes)
-		f32 := format32(t.DataType, e32).(uint32)
-		return scaleUint32(t.Scale, f32)
+		return scaleUint32(t.Scale, e32)
 	case "INT32":
 		e32 := convertEndianness32(t.ByteOrder, bytes)
-		return format32(t.DataType, e32)
+		f32 := int32(e32)
+		return scaleInt32(t.Scale, f32)
 	case "FLOAT32-IEEE":
 		e32 := convertEndianness32(t.ByteOrder, bytes)
-		return format32(t.DataType, e32)
+		f32 := math.Float32frombits(e32)
+		return scaleFloat32(t.Scale, f32)
 	case "FLOAT32":
 		if len(bytes) == 2 {
 			e16 := convertEndianness16(t.ByteOrder, bytes)
-			f16 := format16(t.DataType, e16).(uint16)
-			return scale16toFloat32(t.Scale, f16)
+			return scale16toFloat32(t.Scale, e16)
 		} else {
 			e32 := convertEndianness32(t.ByteOrder, bytes)
 			return scale32toFloat32(t.Scale, e32)
@@ -568,6 +567,14 @@ func scaleUint32(s float64, v uint32) uint32 {
 	return uint32(float64(v) * float64(s))
 }
 
+func scaleInt32(s float64, v int32) int32 {
+	return int32(float64(v) * float64(s))
+}
+
+func scaleFloat32(s float64, v float32) float32 {
+	return float32(float64(v) * s)
+}
+
 // Gather implements the telegraf plugin interface method for data accumulation
 func (m *Modbus) Gather(acc telegraf.Accumulator) error {
 	if !m.isConnected {
diff --git a/plugins/inputs/modbus/modbus_test.go b/plugins/inputs/modbus/modbus_test.go
index 3317067a8..e346ece17 100644
--- a/plugins/inputs/modbus/modbus_test.go
+++ b/plugins/inputs/modbus/modbus_test.go
@@ -239,6 +239,16 @@ func TestHoldingRegisters(t *testing.T) {
 			write:     []byte{0xAB, 0xCD},
 			read:      int16(-12885),
 		},
+		{
+			name:      "register50_register51_abcd_int32_scaled",
+			address:   []uint16{50, 51},
+			quantity:  2,
+			byteOrder: "ABCD",
+			dataType:  "INT32",
+			scale:     10,
+			write:     []byte{0x00, 0x00, 0xAB, 0xCD},
+			read:      int32(439810),
+		},
 		{
 			name:      "register50_register51_abcd_int32",
 			address:   []uint16{50, 51},
@@ -329,6 +339,16 @@ func TestHoldingRegisters(t *testing.T) {
 			write:     []byte{0xAA, 0xBB, 0xCC, 0xDD},
 			read:      float32(-3.3360025e-13),
 		},
+		{
+			name:      "register130_register131_abcd_float32_ieee_scaled",
+			address:   []uint16{130, 131},
+			quantity:  2,
+			byteOrder: "ABCD",
+			dataType:  "FLOAT32-IEEE",
+			scale:     10,
+			write:     []byte{0xAA, 0xBB, 0xCC, 0xDD},
+			read:      float32(-3.3360025e-12),
+		},
 	}
 
 	serv := mbserver.NewServer()