new rtu.

pymodbus/framer/base.py

@@ -6,6 +6,8 @@
 """
 from __future__ import annotations
 
+from abc import abstractmethod
+
 
 class FramerBase:
     """Intern base."""
@@ -21,6 +23,7 @@ def set_dev_ids(self, _dev_ids: list[int]):
     def set_fc_calc(self, _fc: int, _msg_size: int, _count_pos: int):
         """Set/Update function code information."""
 
+    @abstractmethod
     def decode(self, data: bytes) -> tuple[int, int, int, bytes]:
         """Decode ADU.
 
@@ -31,6 +34,7 @@ def decode(self, data: bytes) -> tuple[int, int, int, bytes]:
             modbus request/response (bytes)
         """
 
+    @abstractmethod
     def encode(self, pdu: bytes, dev_id: int, tid: int) -> bytes:
         """Encode ADU.
 

pymodbus/framer/framer.py

@@ -66,13 +66,19 @@ def __init__(self,
         super().__init__(params, is_server)
         self.device_ids = device_ids
         self.broadcast: bool = (0 in device_ids)
+        self.handle1 = FramerRaw()
+        self.handle2 = FramerAscii()
+        self.handle3 = FramerRTU()
+        self.handle4 = FramerSocket()
+        self.handle5 = FramerTLS()
+
         self.handle = {
-            FramerType.RAW: FramerRaw,
-            FramerType.ASCII: FramerAscii,
-            FramerType.RTU: FramerRTU,
-            FramerType.SOCKET: FramerSocket,
-            FramerType.TLS: FramerTLS,
-        }[framer_type]()
+            FramerType.RAW: FramerRaw(),
+            FramerType.ASCII: FramerAscii(),
+            FramerType.RTU: FramerRTU(),
+            FramerType.SOCKET: FramerSocket(),
+            FramerType.TLS: FramerTLS(),
+        }[framer_type]
 
 
     def callback_data(self, data: bytes, addr: tuple | None = None) -> int:

pymodbus/framer/raw.py

@@ -27,6 +27,6 @@ def decode(self, data: bytes) -> tuple[int, int, int, bytes]:
         tid = int(data[1])
         return len(data), dev_id, tid, data[2:]
 
-    def encode(self, pdu: bytes, device_id: int, tid: int) -> bytes:
+    def encode(self, pdu: bytes, dev_id: int, tid: int) -> bytes:
         """Encode ADU."""
-        return device_id.to_bytes(1, 'big') + tid.to_bytes(1, 'big') + pdu
+        return dev_id.to_bytes(1, 'big') + tid.to_bytes(1, 'big') + pdu

pymodbus/framer/rtu.py

@@ -1,6 +1,8 @@
 """Modbus RTU frame implementation."""
 from __future__ import annotations
 
+from collections import namedtuple
+
 from pymodbus.framer.base import FramerBase
 from pymodbus.logging import Log
 
@@ -15,7 +17,7 @@ class FramerRTU(FramerBase):
     neither when receiving nor when sending.
 
     Decoding is a complicated process because the RTU frame does not have a fixed prefix
-    only suffix, therefore it is nessecary to decode the content (PDU) to get length etc.
+    only suffix, therefore it is necessary to decode the content (PDU) to get length etc.
 
     There are some restraints however that help the detection.
 
@@ -43,16 +45,19 @@ class FramerRTU(FramerBase):
        - data in frame garbled (wrong CRC)
     decoding assumes the frame is sound, and if not enters a hunting mode.
 
-    The 3.5 byte wait betwen frames is 31ms at 1.200Bps and 1ms at 38.600bps,
-    so the decoder will wait 50ms for more data if not the transmission is
+    The 3.5 byte wait 31ms at 1.200Bps and 1ms at 38.600bps,
+    so the decoder will wait for more data a number of milliseconds, if not the transmission is
     considered complete
     """
 
     MIN_SIZE = 5
 
+    FC_LEN = namedtuple("FC_LEN", "req_len req_bytepos resp_len resp_bytepos")
+
     def __init__(self) -> None:
         """Initialize a ADU instance."""
         super().__init__()
+        self.fc_len: dict[int, FramerRTU.FC_LEN] = {}
 
 
     @classmethod
@@ -74,6 +79,14 @@ def generate_crc16_table(cls) -> list[int]:
         return result
     crc16_table: list[int] = [0]
 
+
+    def setup_fc_len(self, _fc: int,
+        _req_len: int, _req_byte_pos: int,
+        _resp_len: int, _resp_byte_pos: int
+    ):
+        """Define request/response lengths pr function code."""
+        return
+
     def decode(self, data: bytes) -> tuple[int, int, int, bytes]:
         """Decode ADU."""
         if (buf_len := len(data)) < self.MIN_SIZE: