Add FLOAT64-IEEE support to inputs.modbus (#8361) (by @Nemecsek)

plugins/inputs/modbus/README.md

@@ -67,7 +67,7 @@ Registers via Modbus TCP or Modbus RTU/ASCII.
   ##  |---BA, DCBA   - Little Endian
   ##  |---BADC       - Mid-Big Endian
   ##  |---CDAB       - Mid-Little Endian
-  ## data_type  - INT16, UINT16, INT32, UINT32, INT64, UINT64, FLOAT32-IEEE (the IEEE 754 binary representation)
+  ## data_type  - INT16, UINT16, INT32, UINT32, INT64, UINT64, FLOAT32-IEEE, FLOAT64-IEEE (the IEEE 754 binary representation)
   ##              FLOAT32 (deprecated), FIXED, UFIXED (fixed-point representation on input)
   ## scale      - the final numeric variable representation
   ## address    - variable address
@@ -105,10 +105,10 @@ and cannot be configured.
 
 These types are used for integer input values. Select the one that matches your modbus data source.
 
-#### Floating Point: `FLOAT32-IEEE`
+#### Floating Point: `FLOAT32-IEEE`, `FLOAT64-IEEE`
 
-Use this type if your modbus registers contain a value that is encoded in this format. This type
-always includes the sign and therefore there exists no variant.
+Use these types if your modbus registers contain a value that is encoded in this format. These types
+always include the sign and therefore there exists no variant.
 
 #### Fixed Point: `FIXED`, `UFIXED` (`FLOAT32`)
 

plugins/inputs/modbus/modbus.go

@@ -132,7 +132,8 @@ const sampleConfig = `
   ##  |---BA, DCBA   - Little Endian
   ##  |---BADC       - Mid-Big Endian
   ##  |---CDAB       - Mid-Little Endian
-  ## data_type  - INT16, UINT16, INT32, UINT32, INT64, UINT64, FLOAT32-IEEE (the IEEE 754 binary representation)
+  ## data_type  - INT16, UINT16, INT32, UINT32, INT64, UINT64,
+  ##              FLOAT32-IEEE, FLOAT64-IEEE (the IEEE 754 binary representation)
   ##              FLOAT32, FIXED, UFIXED (fixed-point representation on input)
   ## scale      - the final numeric variable representation
   ## address    - variable address
@@ -355,7 +356,7 @@ func validateFieldContainers(t []fieldContainer, n string) error {
 
 			// search data type
 			switch item.DataType {
-			case "UINT16", "INT16", "UINT32", "INT32", "UINT64", "INT64", "FLOAT32-IEEE", "FLOAT32", "FIXED", "UFIXED":
+			case "UINT16", "INT16", "UINT32", "INT32", "UINT64", "INT64", "FLOAT32-IEEE", "FLOAT64-IEEE", "FLOAT32", "FIXED", "UFIXED":
 				break
 			default:
 				return fmt.Errorf("invalid data type '%s' in '%s' - '%s'", item.DataType, n, item.Name)
@@ -512,6 +513,10 @@ func convertDataType(t fieldContainer, bytes []byte) interface{} {
 		e32 := convertEndianness32(t.ByteOrder, bytes)
 		f32 := math.Float32frombits(e32)
 		return scaleFloat32(t.Scale, f32)
+	case "FLOAT64-IEEE":
+		e64 := convertEndianness64(t.ByteOrder, bytes)
+		f64 := math.Float64frombits(e64)
+		return scaleFloat64(t.Scale, f64)
 	case "FIXED":
 		if len(bytes) == 2 {
 			e16 := convertEndianness16(t.ByteOrder, bytes)
@@ -662,6 +667,10 @@ func scaleFloat32(s float64, v float32) float32 {
 	return float32(float64(v) * s)
 }
 
+func scaleFloat64(s float64, v float64) float64 {
+	return v * s
+}
+
 func scaleUint64(s float64, v uint64) uint64 {
 	return uint64(float64(v) * float64(s))
 }

plugins/inputs/modbus/modbus_test.go

@@ -549,6 +549,66 @@ func TestHoldingRegisters(t *testing.T) {
 			write:     []byte{0xF6, 0x84, 0xF9, 0x45, 0xFE, 0xBC, 0xFF, 0xFF},
 			read:      uint64(18446742686322259968),
 		},
+		{
+			name:      "register214_to_register217_abcdefgh_float64_ieee",
+			address:   []uint16{214, 215, 216, 217},
+			quantity:  4,
+			byteOrder: "ABCDEFGH",
+			dataType:  "FLOAT64-IEEE",
+			scale:     1,
+			write:     []byte{0xBF, 0x9C, 0x6A, 0x40, 0xC3, 0x47, 0x8F, 0x55},
+			read:      float64(-0.02774907295123737),
+		},
+		{
+			name:      "register214_to_register217_abcdefgh_float64_ieee_scaled",
+			address:   []uint16{214, 215, 216, 217},
+			quantity:  4,
+			byteOrder: "ABCDEFGH",
+			dataType:  "FLOAT64-IEEE",
+			scale:     0.1,
+			write:     []byte{0xBF, 0x9C, 0x6A, 0x40, 0xC3, 0x47, 0x8F, 0x55},
+			read:      float64(-0.002774907295123737),
+		},
+		{
+			name:      "register218_to_register221_abcdefgh_float64_ieee_pos",
+			address:   []uint16{218, 219, 220, 221},
+			quantity:  4,
+			byteOrder: "ABCDEFGH",
+			dataType:  "FLOAT64-IEEE",
+			scale:     1,
+			write:     []byte{0x3F, 0x9C, 0x6A, 0x40, 0xC3, 0x47, 0x8F, 0x55},
+			read:      float64(0.02774907295123737),
+		},
+		{
+			name:      "register222_to_register225_hgfecdba_float64_ieee",
+			address:   []uint16{222, 223, 224, 225},
+			quantity:  4,
+			byteOrder: "HGFEDCBA",
+			dataType:  "FLOAT64-IEEE",
+			scale:     1,
+			write:     []byte{0x55, 0x8F, 0x47, 0xC3, 0x40, 0x6A, 0x9C, 0xBF},
+			read:      float64(-0.02774907295123737),
+		},
+		{
+			name:      "register226_to_register229_badcfehg_float64_ieee",
+			address:   []uint16{226, 227, 228, 229},
+			quantity:  4,
+			byteOrder: "BADCFEHG",
+			dataType:  "FLOAT64-IEEE",
+			scale:     1,
+			write:     []byte{0x9C, 0xBF, 0x40, 0x6A, 0x47, 0xC3, 0x55, 0x8F},
+			read:      float64(-0.02774907295123737),
+		},
+		{
+			name:      "register230_to_register233_ghefcdab_float64_ieee",
+			address:   []uint16{230, 231, 232, 233},
+			quantity:  4,
+			byteOrder: "GHEFCDAB",
+			dataType:  "FLOAT64-IEEE",
+			scale:     1,
+			write:     []byte{0x8F, 0x55, 0xC3, 0x47, 0x6A, 0x40, 0xBF, 0x9C},
+			read:      float64(-0.02774907295123737),
+		},
 	}
 
 	serv := mbserver.NewServer()