implement reset command

meer_tec/mecom.py

@@ -1,18 +1,20 @@
 import random
 import struct
-from typing import Generic, Optional, Type, TypeVar
+from typing import Generic, Literal, Optional, Type, TypeVar
 
 from PyCRC.CRCCCITT import CRCCCITT as CRC
 
+PARAM_CMDS = ["VS", "?VR"]
 FloatOrInt = TypeVar("FloatOrInt", float, int)
+ParamCmds = Literal["VS", "?VR"]
 
 
 def calc_checksum(string: str) -> str:
     """Calculate CRC checksum."""
     return f"{CRC().calculate(string):04X}"
 
 
-def construct_mecom_cmd(
+def construct_param_cmd(
     device_addr: int,
     cmd: str,
     param_id: int,
@@ -36,10 +38,23 @@ def construct_mecom_cmd(
     :return: MeCom command
     """
     if seq_num is None:
-        # generate a random request number if none is given
         seq_num = random.randint(0, 65535)
 
+    if seq_num < 0 or seq_num > 65535:
+        raise ValueError("seq_num must be between 0 and 65535")
+
+    if cmd not in PARAM_CMDS:
+        raise ValueError(f"cmd must be one of {PARAM_CMDS}")
+
+    if device_addr < 0 or device_addr > 255:
+        raise ValueError("device_addr must be between 0 and 255")
+
+    if cmd in ["VS", "?VR"] and param_id is None:
+        raise ValueError("param_id must be given for VS and ?VR commands")
+
     if cmd == "VS":
+        if value is None:
+            raise ValueError("value must be given for VS command")
         if value_type is float:
             # convert float to hex of length 8, remove the leading '0X' and capitalize
             val = hex(struct.unpack("<I", struct.pack("<f", value))[0])[2:].upper()
@@ -53,7 +68,34 @@ def construct_mecom_cmd(
     return f"{cmd}{calc_checksum(cmd)}\r"
 
 
+def construct_reset_cmd(device_addr: int, seq_num: Optional[int] = None) -> str:
+    """
+    Construct a MeCom reset command.
+
+    :param device_addr: Device address (0 .. 255). Broadcast Device Address (0) will
+        send the command to all connected Meerstetter devices
+    :param seq_num: Sequence number (0 .. 65535). If not given, a random number will be
+        generated
+    :return: MeCom command
+    """
+    if seq_num is None:
+        seq_num = random.randint(0, 65535)
+
+    if seq_num < 0 or seq_num > 65535:
+        raise ValueError("seq_num must be between 0 and 65535")
+
+    cmd = f"#{device_addr:02X}{seq_num:04X}RS"
+    return f"{cmd}{calc_checksum(cmd)}\r"
+
+
 def verify_response(reponse: "Message", request: "Message") -> bool:
+    """
+    Verify a MeCom response.
+
+    :param reponse: MeCom response
+    :param request: MeCom request
+    :return: True if response is valid, False otherwise
+    """
     checksum_correct = reponse.checksum == calc_checksum(reponse[0:-5])
     request_match = reponse.seq_num == request.seq_num
     return checksum_correct & request_match

meer_tec/tec.py

@@ -1,7 +1,7 @@
 from typing import Optional, Type
 
 from .interfaces import Interface, Message
-from .mecom import FloatOrInt, construct_mecom_cmd
+from .mecom import FloatOrInt, construct_param_cmd, construct_reset_cmd, verify_response
 
 
 class TEC:
@@ -19,7 +19,7 @@ def get_parameter(
         seq_num: Optional[int] = None,
         param_inst: int = 1,
     ) -> FloatOrInt:
-        cmd = construct_mecom_cmd(
+        cmd = construct_param_cmd(
             device_addr=self.device_addr,
             cmd="?VR",
             param_id=param_id,
@@ -41,7 +41,7 @@ def set_parameter(
         seq_num: Optional[int] = None,
         param_inst: int = 1,
     ) -> None:
-        cmd = construct_mecom_cmd(
+        cmd = construct_param_cmd(
             device_addr=self.device_addr,
             cmd="VS",
             param_id=param_id,
@@ -52,12 +52,16 @@ def set_parameter(
         )
         request = Message(cmd, value_type)
         reponse = Message(self.interface.query(request), value_type=value_type)
+        if not verify_response(reponse, request):
+            raise ValueError("Response does not match request")
         print(reponse)
 
     def reset(self) -> None:
-        # FIXME: Could not find this in the documentation
-        # self.set_parameter("?RS", value_type=int)
-        raise NotImplementedError
+        cmd = construct_reset_cmd(device_addr=self.device_addr)
+        request = Message(cmd, value_type=int)
+        reponse = Message(self.interface.query(request), value_type=int)
+        if not verify_response(reponse, request):
+            raise ValueError("Response does not match request")
 
     # Common product parameters
 

tests/test_mecom.py

@@ -1,10 +1,10 @@
-from meer_tec.mecom import construct_mecom_cmd
+from meer_tec.mecom import construct_param_cmd, construct_reset_cmd
 
 
 def test_vs_float() -> None:
     # created with https://www.meerstetter.ch/MeCom/
     CMD = "#7BEF32VS03E8E641C8CCCDE2C1\r"
-    cmd = construct_mecom_cmd(
+    cmd = construct_param_cmd(
         device_addr=123,
         cmd="VS",
         param_id=1000,
@@ -19,7 +19,7 @@ def test_vs_float() -> None:
 def test_vr_float() -> None:
     # created with https://www.meerstetter.ch/MeCom/
     CMD = "#7BEF32?VR03E8E69AAD\r"
-    cmd = construct_mecom_cmd(
+    cmd = construct_param_cmd(
         device_addr=123,
         cmd="?VR",
         param_id=1000,
@@ -32,7 +32,7 @@ def test_vr_float() -> None:
 
 def test_vs_int() -> None:
     CMD = "#E6EA5FVS07E57B0000001958B0\r"
-    cmd = construct_mecom_cmd(
+    cmd = construct_param_cmd(
         device_addr=230,
         cmd="VS",
         param_id=2021,
@@ -46,7 +46,7 @@ def test_vs_int() -> None:
 
 def test_vr_int() -> None:
     CMD = "#E6EA5F?VR07E57BB3B5\r"
-    cmd = construct_mecom_cmd(
+    cmd = construct_param_cmd(
         device_addr=230,
         cmd="?VR",
         param_id=2021,
@@ -55,3 +55,9 @@ def test_vr_int() -> None:
         seq_num=59999,
     )
     assert cmd == CMD
+
+
+def test_reset() -> None:
+    CMD = "#7B3039RSB5BB\r"
+    cmd = construct_reset_cmd(device_addr=123, seq_num=12345)
+    assert cmd == CMD