enable polling explicitly for ObservationField devices

tangostationcontrol/tangostationcontrol/devices/observation_field.py

@@ -15,6 +15,7 @@ from jsonschema.exceptions import ValidationError
 from tango import AttrWriteType, DeviceProxy, DevState, Util
 from tango.server import attribute
 from tangostationcontrol.common.constants import (
+    DEFAULT_METRICS_POLLING_PERIOD,
     DEFAULT_POLLING_PERIOD,
     MAX_ANTENNA,
     N_beamlets_ctrl,
@@ -308,6 +309,10 @@ class ObservationField(LOFARDevice):
             self._observation_field_settings.antenna_field,
         )
 
+        # TODO(JDM): Somehow this does not get configured automatically
+        # as it does for non-dynamic devices.
+        self.poll_command("poll_attributes", DEFAULT_METRICS_POLLING_PERIOD)
+
     def configure_for_off(self):
         """Indicate the observation has stopped"""