fix GPIB transport casting to SCPIDevice

Author: rambo

src/scpi/scpi.py

@@ -140,7 +140,7 @@ def error_available(self) -> int:
 class SCPIProtocol:
     """Implements the SCPI protocol talks over the given transport"""
 
-    transport: BaseTransport = field()
+    transport: Union[BaseTransport, GPIBDeviceTransport, GPIBTransport] = field()
     lock: asyncio.Lock = field(default_factory=asyncio.Lock)
     _checking_error: bool = field(default=False)
 
@@ -249,7 +249,7 @@ def __post_init__(self) -> None:
         protocol: Optional[SCPIProtocol] = None
         if isinstance(self.instancefrom, SCPIProtocol):
             protocol = self.instancefrom
-        if isinstance(self.instancefrom, BaseTransport):
+        if isinstance(self.instancefrom, (BaseTransport, GPIBDeviceTransport, GPIBTransport)):
             protocol = SCPIProtocol(self.instancefrom)
         if isinstance(self.instancefrom, SCPIDevice):
             protocol = self.instancefrom.protocol

src/scpi/transports/gpib/base.py

@@ -59,6 +59,10 @@ async def send_loc(self) -> None:
         await self._set_ll_address()
         await self.lltransport.send_loc()
 
+    async def quit(self) -> None:
+        """Nop for devices"""
+        LOGGER.debug("quit should not be called on device level but we must have the method for type compatibility")
+
 
 class GPIBTransport(BaseTransport, ABC):
     """Baseclass for GPIB transports"""

src/scpi/transports/gpib/prologix.py

@@ -159,7 +159,7 @@ async def scan_devices(self) -> Sequence[Tuple[int, str]]:
         found_addresses: List[int] = []
         # We do not lock on this level since the commands we use need to manipulate the lock
         prev_addr = await self.query_address()
-        prev_read_tmo_ms = await self.send_and_read("++read_tmo_ms")
+        prev_read_tmo_ms = int(await self.send_and_read("++read_tmo_ms"))
         new_read_tmo_ms = int((SCAN_DEVICE_TIMEOUT / 2) * 1000)
         self._serialhandler.protocol.write_line(f"++read_tmo_ms {new_read_tmo_ms:d}")
         for addr in range(0, 31):  # 0-30 inclusive