diff --git a/components/actor/heater_hendi.py b/components/actor/heater_hendi.py
index aae2b9f..8454b11 100755
--- a/components/actor/heater_hendi.py
+++ b/components/actor/heater_hendi.py
@@ -34,28 +34,49 @@ class HeaterHendi(AHeater):
 	def activate(self, enable):
 		if not self.connected:
 			return
-		if enable:
-			self.hendi.remoteEnable(1)
-		else:
-			self.hendi.setSwitch(0)
+		try:
+			if enable:
+				self.hendi.remoteEnable(1)
+			else:
+				self.hendi.setSwitch(0)
+		except Exception as e:
+			# A device that was connected can still fail a live command (the
+			# hendi's own idle-timeout auto-suspend, a cable pulled mid-run,
+			# ...) - treat that the same as a disconnect rather than letting
+			# it escape uncaught, since this is called both from HeaterTask's
+			# tick loop (with self.device.open(): activate(True)/(False)) and
+			# from a client's Connect/Disconnect command, neither of which
+			# expect activate() itself to ever raise.
+			print(f"HeaterHendi: comm error in activate({enable}): {e}")
+			self.disconnect()
 
 	def is_activated(self):
 		if not self.connected:
 			return False
-		s = self.hendi.isRemoteEnable()
-		return '1' in s
+		try:
+			s = self.hendi.isRemoteEnable()
+			return '1' in s
+		except Exception as e:
+			print(f"HeaterHendi: comm error in is_activated: {e}")
+			self.disconnect()
+			return False
 
 	def process(self):
 		if not self.connected:
 			self.power_eff = 0
 			return
-		power = self.power_set
-		if power == 0:
-			self.hendi.setSwitch(0)
-		else:
-			self.hendi.setSwitch(1)
-		self.hendi.setPowerWatts(power)
-		self.power_eff = self.hendi.getPowerWatts() if power > 0 else 0
+		try:
+			power = self.power_set
+			if power == 0:
+				self.hendi.setSwitch(0)
+			else:
+				self.hendi.setSwitch(1)
+			self.hendi.setPowerWatts(power)
+			self.power_eff = self.hendi.getPowerWatts() if power > 0 else 0
+		except Exception as e:
+			print(f"HeaterHendi: comm error in process: {e}")
+			self.disconnect()
+			self.power_eff = 0
 
 	def set_power(self, power):
 		self.power_set = min(self.get_power_max(), power)
diff --git a/components/actor/stirrerpololu1376.py b/components/actor/stirrerpololu1376.py
index 7f76902..b809740 100644
--- a/components/actor/stirrerpololu1376.py
+++ b/components/actor/stirrerpololu1376.py
@@ -47,27 +47,45 @@ class StirrerPololu1376(AStirrer):
 	def activate(self, enable):
 		if not self.connected:
 			return
-		print("activate {}".format(enable))
-		if enable:
-			self.drv.go()
-		else:
-			self.drv.stop()
+		try:
+			print("activate {}".format(enable))
+			if enable:
+				self.drv.go()
+			else:
+				self.drv.stop()
+		except Exception as e:
+			# See HeaterHendi.activate()'s own comment: a device that was
+			# connected can still fail a live command (cable pulled
+			# mid-run, ...) - this is called both from StirrerTask's tick
+			# loop (with self.device.open(): activate(True)/(False)) and
+			# from a client's Connect/Disconnect command, neither of which
+			# expect activate() itself to ever raise.
+			print(f"StirrerPololu1376: comm error in activate({enable}): {e}")
+			self.disconnect()
 
 	def _on_set_speed(self, speed):
 		if not self.connected:
 			return
-		self.drv.motor_forward(speed)
-		print("Set speed to {} %".format(speed))
+		try:
+			self.drv.motor_forward(speed)
+			print("Set speed to {} %".format(speed))
+		except Exception as e:
+			print(f"StirrerPololu1376: comm error in _on_set_speed: {e}")
+			self.disconnect()
 
 	def _on_process(self):
 		if not self.connected:
 			return
-		status = self.drv.get_variable(Varid.STATUS)
-		limit_status = self.drv.get_variable(Varid.STATUS_LIMIT_STATUS)
-		if status & 0x01 == 0x01:
-			if limit_status & 0x01 == 0x01:
-				print("Recover after motor error!")
-				self.drv.go()
+		try:
+			status = self.drv.get_variable(Varid.STATUS)
+			limit_status = self.drv.get_variable(Varid.STATUS_LIMIT_STATUS)
+			if status & 0x01 == 0x01:
+				if limit_status & 0x01 == 0x01:
+					print("Recover after motor error!")
+					self.drv.go()
+		except Exception as e:
+			print(f"StirrerPololu1376: comm error in _on_process: {e}")
+			self.disconnect()
 		
 
 if __name__ == '__main__':