refactor and combine for EPICS scan_id PV (#280)

* MNT #229 refactor

* STY #229 per 'ruff check'

bluesky/instrument/epics_signal_config.py

@@ -9,16 +9,16 @@
 
 import logging
 
+from ophyd.signal import EpicsSignalBase
+
 logger = logging.getLogger(__name__)
 logger.info(__file__)
 
-from . import iconfig
-from ophyd.signal import EpicsSignal
-from ophyd.signal import EpicsSignalBase
+from . import iconfig  # noqa
 
 
-# set default timeout for all EpicsSignal connections & communications
-# always first, before ANY ophyd EPICS-based signals are created
+# Set default timeout for all EpicsSignal connections & communications.
+# Always call first, before ANY ophyd EPICS-based signals are created.
 TIMEOUT = 60
 if not EpicsSignalBase._EpicsSignalBase__any_instantiated:
     EpicsSignalBase.set_defaults(
@@ -33,25 +33,32 @@
     logger.info("Using RunEngine metadata for scan_id")
     scan_id_epics = None
 else:
+    from ophyd.signal import EpicsSignal
+
     logger.info("Using EPICS PV %s for scan_id", pvname)
+    # Must not call _before_ default timeouts are set.
     scan_id_epics = EpicsSignal(pvname, name="scan_id_epics")
 
 
 def epics_scan_id_source(*args, **kwargs):
     """
     Callback function for RunEngine.  Returns *next* scan_id to be used.
 
+    * Ignore args and kwargs.
     * Get current scan_id from PV.
     * Apply lower limit of zero.
     * Increment.
     * Set PV with new value.
     * Return new value.
+
+    Exception will be raised if PV is not connected when next
+    ``bluesky.plan_stubs.open_run()`` is called.
     """
     if scan_id_epics is None:
         raise RuntimeError(
             "epics_scan_id_source() called when"
             " 'RUN_ENGINE_SCAN_ID_PV' is"
-            "undefined in 'iconfig.yml' file."
+            " undefined in 'iconfig.yml' file."
         )
     new_scan_id = max(scan_id_epics.get(), 0) + 1
     scan_id_epics.put(new_scan_id)

bluesky/instrument/framework/initialize.py

@@ -109,47 +109,14 @@ def get_md_path():
 # diagnostics
 # RE.msg_hook = ts_msg_hook
 
-# set default timeout for all EpicsSignal connections & communications
-TIMEOUT = 60
-if not EpicsSignalBase._EpicsSignalBase__any_instantiated:
-    EpicsSignalBase.set_defaults(
-        auto_monitor=True,
-        timeout=iconfig.get("PV_READ_TIMEOUT", TIMEOUT),
-        write_timeout=iconfig.get("PV_WRITE_TIMEOUT", TIMEOUT),
-        connection_timeout=iconfig.get("PV_CONNECTION_TIMEOUT", TIMEOUT),
-    )
-
-# Create a registry of ophyd devices
-registry = Registry(auto_register=True)
-
-_pv = iconfig.get("RUN_ENGINE_SCAN_ID_PV")
-if _pv is None:
-    logger.info("Using RunEngine metadata for scan_id")
-else:
-    from ophyd import EpicsSignal
-
-    logger.info("Using EPICS PV %s for scan_id", _pv)
-    scan_id_epics = EpicsSignal(_pv, name="scan_id_epics")
-
-    def epics_scan_id_source(_md):
-        """
-        Callback function for RunEngine.  Returns *next* scan_id to be used.
-
-        * Ignore metadata dictionary passed as argument.
-        * Get current scan_id from PV.
-        * Apply lower limit of zero.
-        * Increment (so that scan_id numbering starts from 1).
-        * Set PV with new value.
-        * Return new value.
-
-        Exception will be raised if PV is not connected when next
-        ``bps.open_run()`` is called.
-        """
-        new_scan_id = max(scan_id_epics.get(), 0) + 1
-        scan_id_epics.put(new_scan_id)
-        return new_scan_id
+if iconfig.get("RUN_ENGINE_SCAN_ID_PV") is not None:
+    from ..epics_signal_config import epics_scan_id_source
+    from ..epics_signal_config import scan_id_epics
 
     # tell RunEngine to use the EPICS PV to provide the scan_id.
     RE.scan_id_source = epics_scan_id_source
     scan_id_epics.wait_for_connection()
     RE.md["scan_id"] = scan_id_epics.get()
+
+# Create a registry of ophyd devices
+registry = Registry(auto_register=True)