Handle "little" for multiple values in to_registers (#2678)

Author: igorbga

pymodbus/client/mixin.py

@@ -771,5 +771,19 @@ def convert_to_registers(
             for x in range(0, len(byte_list), 2)
         ]
         if word_order == "little":
-            regs.reverse()
+            return cls._get_reversed_registers(regs, data_type)
+
         return regs
+
+    @classmethod
+    def _get_reversed_registers(cls, regs: list[int], data_type: DATATYPE) -> list[int]:
+        if not (data_type_len := data_type.value[1]):
+            regs.reverse()
+            return regs
+
+        reversed_regs: list[int] = []
+        for x in range(0, len(regs), data_type_len):
+            single_value_regs = regs[x: x + data_type_len]
+            single_value_regs.reverse()
+            reversed_regs = reversed_regs + single_value_regs
+        return reversed_regs

test/client/test_client.py

@@ -105,9 +105,22 @@ def fake_execute(_self, _no_response_expected, request):
             (ModbusClientMixin.DATATYPE.STRING, "a", [0x6100], None),
             (ModbusClientMixin.DATATYPE.UINT16, 27123, [0x69F3], None),
             (ModbusClientMixin.DATATYPE.INT16, -27123, [0x960D], None),
+            (ModbusClientMixin.DATATYPE.INT16, [-27123, 27123], [0x960D, 0x69F3], None),
             (ModbusClientMixin.DATATYPE.UINT32, 27123, [0x0000, 0x69F3], None),
             (ModbusClientMixin.DATATYPE.UINT32, 32145678, [0x01EA, 0x810E], None),
+            (
+                ModbusClientMixin.DATATYPE.UINT32,
+                [27123, 32145678],
+                [0x0000, 0x69F3, 0x01EA, 0x810E],
+                None
+            ),
             (ModbusClientMixin.DATATYPE.INT32, -32145678, [0xFE15, 0x7EF2], None),
+            (
+                ModbusClientMixin.DATATYPE.INT32,
+                [32145678, -32145678],
+                [0x01EA, 0x810E, 0xFE15, 0x7EF2],
+                None
+            ),
             (
                 ModbusClientMixin.DATATYPE.UINT64,
                 1234567890123456789,
@@ -120,9 +133,21 @@ def fake_execute(_self, _no_response_expected, request):
                 [0xEEDD, 0xEF0B, 0x8216, 0x7EEB],
                 None,
             ),
+            (
+                ModbusClientMixin.DATATYPE.INT64,
+                [1234567890123456789, -1234567890123456789],
+                [0x1122, 0x10F4, 0x7DE9, 0x8115, 0xEEDD, 0xEF0B, 0x8216, 0x7EEB],
+                None,
+            ),
             (ModbusClientMixin.DATATYPE.FLOAT32, 27123.5, [0x46D3, 0xE700], None),
             (ModbusClientMixin.DATATYPE.FLOAT32, 3.141592, [0x4049, 0x0FD8], None),
             (ModbusClientMixin.DATATYPE.FLOAT32, -3.141592, [0xC049, 0x0FD8], None),
+            (
+                ModbusClientMixin.DATATYPE.FLOAT32,
+                [27123.5, 3.141592, -3.141592],
+                [0x46D3, 0xE700, 0x4049, 0x0FD8, 0xC049, 0x0FD8],
+                None
+            ),
             (ModbusClientMixin.DATATYPE.FLOAT64, 27123.5, [0x40DA, 0x7CE0, 0x0000, 0x0000], None),
             (
                 ModbusClientMixin.DATATYPE.FLOAT64,
@@ -136,6 +161,12 @@ def fake_execute(_self, _no_response_expected, request):
                 [0xC009, 0x21FB, 0x5444, 0x2D11],
                 None,
             ),
+            (
+                ModbusClientMixin.DATATYPE.FLOAT64,
+                [3.14159265358979, -3.14159265358979],
+                [0x4009, 0x21FB, 0x5444, 0x2D11, 0xC009, 0x21FB, 0x5444, 0x2D11],
+                None,
+            ),
             (
                 ModbusClientMixin.DATATYPE.BITS,
                 [True],
@@ -195,7 +226,16 @@ def fake_execute(_self, _no_response_expected, request):
     def test_client_mixin_convert(self, datatype, word_order, registers, value, string_encoding):
         """Test converter methods."""
         if word_order == "little":
-            registers = list(reversed(registers))
+            if not (datatype_len := datatype.value[1]):
+                registers = list(reversed(registers))
+            else:
+                reversed_regs: list[int] = []
+                for x in range(0, len(registers), datatype_len):
+                    single_value_regs = registers[x: x + datatype_len]
+                    single_value_regs.reverse()
+                    reversed_regs = reversed_regs + single_value_regs
+                registers = reversed_regs
+
 
         kwargs = {**({"word_order": word_order} if word_order else {}),
                   **({"string_encoding": string_encoding} if string_encoding else {})}
@@ -207,7 +247,10 @@ def test_client_mixin_convert(self, datatype, word_order, registers, value, stri
             if (missing := len(value) % 16):
                 value = value + [False] * (16 - missing)
         if datatype == ModbusClientMixin.DATATYPE.FLOAT32:
-            result = round(result, 6)
+            if isinstance(result, list):
+                result = [round(v, 6) for v in result]
+            else:
+                result = round(result, 6)
         assert result == value
 
     @pytest.mark.parametrize(