Improve freezing protection:

- Implement hysteresis to avoid unnecessary cycles
- Prefer internal dome sensor over chiller sensor

chillerd

@@ -47,10 +47,12 @@ class ChillerDaemon:
         self._running = True
         self._port = None
         self._port_error = False
+        self._temperature_error = False
 
         self._mode = ChillerMode.Automatic
         self._request_timestamp = Time('2000-01-01')
         self._request_enabled = False
+        self._antifreeze_enabled = False
 
         self._status = {
             'date': datetime.datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%SZ'),
@@ -142,9 +144,36 @@ class ChillerDaemon:
                     else:
                         status = ChillerStatus.Idle
 
+                    # Prefer dome sensor over chiller sensor (which may be locally warmer due to heat from chiller)
+                    try:
+                        with self._config.temperature_daemon.connect() as daemon:
+                            environment = daemon.last_measurement()
+
+                        if self._config.temperature_valid_key and self._config.temperature_valid_key in environment:
+                            if not environment[self._config.humidity_valid_key]:
+                                if not self._temperature_error:
+                                    self._temperature_error = True
+                                    log.error(self._config.log_name, 'Lost contact with temperature sensor')
+
+                        if self._temperature_error:
+                            self._temperature_error = False
+                            log.info(self._config.log_name, 'Restored contact with temperature sensor')
+
+                        if not self._temperature_error:
+                            ambient = environment[self._config.temperature_value_key]
+
+                    except Exception:
+                        self._temperature_error = True
+                        log.error(self._config.log_name, 'Lost contact with temperature sensor')
+
                     with self._loop_condition:
                         if self._mode == ChillerMode.Automatic:
-                            request_enabled = self._request_timestamp > Time.now() - 1 * u.minute or ambient < 5.0
+                            antifreeze_limit = self._config.antifreeze_enable_limit
+                            if self._antifreeze_enabled:
+                                antifreeze_limit = self._config.antifreeze_disable_limit
+
+                            self._antifreeze_enabled = ambient < antifreeze_limit
+                            request_enabled = self._antifreeze_enabled or self._request_timestamp > Time.now() - 1 * u.minute
                         else:
                             request_enabled = self._request_enabled
 

clasp.json

@@ -6,5 +6,10 @@
   "serial_port": "/dev/chiller",
   "serial_baud": 9600,
   "serial_timeout": 5,
-  "query_delay": 7
+  "query_delay": 7,
+  "temperature_daemon": "clasp_domealert",
+  "temperature_value_key": "internal_humidity",
+  "temperature_valid_key": "internal_humidity_valid",
+  "antifreeze_enable_limit": 5,
+  "antifreeze_disable_limit": 7
 }

rockit/chiller/config.py

@@ -24,7 +24,9 @@
     'additionalProperties': False,
     'required': [
         'daemon', 'log_name', 'control_machines', 'camera_machines',
-        'serial_port', 'serial_baud', 'serial_timeout', 'query_delay'
+        'serial_port', 'serial_baud', 'serial_timeout', 'query_delay',
+        'temperature_daemon', 'temperature_valid_key', 'temperature_value_key',
+        'antifreeze_enable_limit', 'antifreeze_disable_limit'
     ],
     'properties': {
         'daemon': {
@@ -62,10 +64,28 @@
         'query_delay': {
             'type': 'number',
             'min': 0
-        }
+        },
+        'temperature_daemon': {
+            'daemon_name': True,
+            'type': 'string',
+        },
+        'temperature_value_key': {
+            'type': 'string',
+        },
+        'temperature_valid_key': {
+            'type': 'string',
+        },
+        'antifreeze_enable_limit': {
+            'type': 'number'
+        },
+        'antifreeze_disable_limit': {
+            'type': 'number'
+        },
+
     }
 }
 
+
 class Config:
     """Daemon configuration parsed from a json file"""
     def __init__(self, config_filename):
@@ -88,3 +108,11 @@ def __init__(self, config_filename):
         self.serial_baud = int(config_json['serial_baud'])
         self.serial_timeout = int(config_json['serial_timeout'])
         self.query_delay = config_json['query_delay']
+        self.temperature_daemon = getattr(daemons, config_json['temperature_daemon'])
+        self.temperature_value_key = config_json['temperature_value_key']
+        if 'temperature_valid_key' in config_json:
+            self.temperature_valid_key = config_json['temperature_valid_key']
+        else:
+            self.temperature_valid_key = None
+        self.antifreeze_enable_limit = config_json['antifreeze_enable_limit']
+        self.antifreeze_disable_limit = config_json['antifreeze_disable_limit']