diff --git a/simulator/app.py b/simulator/app.py
index a4c0067..2cf4154 100644
--- a/simulator/app.py
+++ b/simulator/app.py
@@ -19,17 +19,17 @@ def status():
 
 @app.route("/battery")
 def battery():
-    return jsonify(pico.get_status()["battery"])
+    return jsonify(pico.get_status().get("battery", {}))
 
 
 @app.route("/temps")
 def temps():
-    return jsonify(pico.get_status()["temps"])
+    return jsonify(pico.get_status().get("temps", {}))
 
 
 @app.route("/relays")
 def relays():
-    return jsonify(pico.get_status()["relays"])
+    return jsonify(pico.get_status().get("relays", {}))
 
 
 @app.route("/relay/<name>", methods=["POST"])
@@ -37,38 +37,65 @@ def set_relay(name):
     data = request.get_json(force=True)
     response = pico.set_relay(name, data.get("state", False))
 
-    if not response["success"]:
-        return jsonify(response), 404
+    if not response.get("success"):
+        return jsonify(response), 503
 
     return jsonify(response)
 
 
 @app.route("/network")
 def network():
-    return jsonify(pico.get_status()["network"])
+    return jsonify(pico.get_status().get("network", {}))
 
 
 @app.route("/network/wifi", methods=["POST"])
 def enable_wifi():
     data = request.get_json(force=True)
     minutes = int(data.get("minutes", 10))
-    return jsonify(pico.enable_wifi(minutes))
+    response = pico.enable_wifi(minutes)
+
+    if not response.get("success"):
+        return jsonify(response), 503
+
+    return jsonify(response)
 
 
 @app.route("/vehicle/ignition", methods=["POST"])
 def toggle_ignition():
-    return jsonify(pico.toggle_ignition())
+    response = pico.toggle_ignition()
+
+    if not response.get("success"):
+        return jsonify(response), 503
+
+    return jsonify(response)
 
 
 @app.route("/sensor/<name>/fault", methods=["POST"])
 def toggle_sensor_fault(name):
     response = pico.toggle_sensor_fault(name)
 
-    if not response["success"]:
-        return jsonify(response), 404
+    if not response.get("success"):
+        return jsonify(response), 503
 
     return jsonify(response)
 
 
+@app.route("/comms")
+def comms():
+    return jsonify(pico.get_comms())
+
+
+@app.route("/comms/rs485/disconnect", methods=["POST"])
+def disconnect_rs485():
+    pico.disconnect_rs485()
+    return jsonify({"success": True, "rs485_connected": False})
+
+
+@app.route("/comms/rs485/restore", methods=["POST"])
+def restore_rs485():
+    pico.restore_rs485()
+    return jsonify({"success": True, "rs485_connected": True})
+
+
 if __name__ == "__main__":
     app.run(host="0.0.0.0", port=5000, debug=True)
diff --git a/simulator/pico_sim.py b/simulator/pico_sim.py
index 70d1821..0456889 100644
--- a/simulator/pico_sim.py
+++ b/simulator/pico_sim.py
@@ -1,5 +1,6 @@
+import time
+
 from protocol import (
-    MessageType,
     status_request,
     set_relay_request,
     enable_wifi_request,
@@ -13,20 +14,65 @@ class PicoSimulator:
         self.controller = controller
         self.last_status = None
         self.primary_link = "rs485"
+        self.rs485_connected = True
         self.backup_link_available = True
+        self.messages_sent = 0
+        self.messages_received = 0
+        self.last_message_time = None
 
     def send_message(self, message):
-        """
-        This simulates the Pico sending a protocol message to the ESP32.
+        self.messages_sent += 1
 
-        Later, this is where RS-485 serial communication will replace
-        the direct Python method call.
-        """
-        return self.controller.handle_message(message)
+        if not self.rs485_connected:
+            return {
+                "type": "error",
+                "success": False,
+                "error": "RS-485 disconnected"
+            }
+
+        response = self.controller.handle_message(message)
+        self.messages_received += 1
+        self.last_message_time = int(time.time())
+        return response
 
     def get_status(self):
         response = self.send_message(status_request())
+
+        if response.get("type") == "error":
+            if self.last_status:
+                self.last_status["network"]["rs485_connected"] = False
+                self.last_status["network"]["communication_lost"] = True
+                self.last_status["network"]["messages_sent"] = self.messages_sent
+                self.last_status["network"]["messages_received"] = self.messages_received
+                self.last_status["network"]["last_message_time"] = self.last_message_time
+                return self.last_status
+
+            return {
+                "timestamp": int(time.time()),
+                "vehicle": {"ignition_on": True},
+                "battery": {},
+                "temps": {},
+                "sensor_health": {},
+                "relays": {},
+                "network": {
+                    "rs485_connected": False,
+                    "communication_lost": True,
+                    "wifi_enabled": False,
+                    "wifi_override_active": False,
+                    "starlink_enabled": False,
+                    "messages_sent": self.messages_sent,
+                    "messages_received": self.messages_received,
+                    "last_message_time": self.last_message_time
+                },
+                "config": {}
+            }
+
         self.last_status = response["data"]
+        self.last_status["network"]["rs485_connected"] = self.rs485_connected
+        self.last_status["network"]["communication_lost"] = False
+        self.last_status["network"]["messages_sent"] = self.messages_sent
+        self.last_status["network"]["messages_received"] = self.messages_received
+        self.last_status["network"]["last_message_time"] = self.last_message_time
         return self.last_status
 
     def set_relay(self, relay, state):
@@ -40,3 +86,19 @@ class PicoSimulator:
 
     def toggle_sensor_fault(self, sensor):
         return self.send_message(toggle_sensor_fault_request(sensor))
+
+    def disconnect_rs485(self):
+        self.rs485_connected = False
+
+    def restore_rs485(self):
+        self.rs485_connected = True
+
+    def get_comms(self):
+        return {
+            "primary": self.primary_link,
+            "backup_available": self.backup_link_available,
+            "rs485_connected": self.rs485_connected,
+            "messages_sent": self.messages_sent,
+            "messages_received": self.messages_received,
+            "last_message_time": self.last_message_time
+        }
diff --git a/simulator/static/style.css b/simulator/static/style.css
index 60eb5bc..9dda027 100644
--- a/simulator/static/style.css
+++ b/simulator/static/style.css
@@ -308,3 +308,19 @@ nav button {
     color: #ffaaaa;
     font-weight: bold;
 }
+
+.comms-lost header {
+    border: 2px solid #b00020;
+    border-radius: 12px;
+    padding: 10px;
+    background: #260808;
+}
+
+.settings-list input[type="checkbox"] {
+    width: 28px;
+    height: 28px;
+}
+
+#config .settings-list {
+    margin-bottom: 18px;
+}
diff --git a/simulator/templates/index.html b/simulator/templates/index.html
index aaa9cee..5c52656 100644
--- a/simulator/templates/index.html
+++ b/simulator/templates/index.html
@@ -90,6 +90,18 @@
         <button onclick="enableWifi()">Enable WiFi 10 min</button>
         <button onclick="toggleIgnition()">Toggle Ignition</button>
 
+        <h2>Communication</h2>
+        <div class="detail-list">
+            <div>Primary Link <strong id="commsPrimary">--</strong></div>
+            <div>Backup Available <strong id="commsBackup">--</strong></div>
+            <div>Messages Sent <strong id="commsSent">--</strong></div>
+            <div>Messages Received <strong id="commsReceived">--</strong></div>
+            <div>Last Message <strong id="commsLast">--</strong></div>
+        </div>
+
+        <button onclick="disconnectRs485()">Disconnect RS-485</button>
+        <button onclick="restoreRs485()">Restore RS-485</button>
+
         <h2>Sensor Fault Simulation</h2>
         <div class="settings-list">
             <button onclick="toggleSensorFault('fridge_zone_1')">Toggle Fridge Zone 1 Fault</button>
@@ -98,35 +110,6 @@
             <button onclick="toggleSensorFault('outside')">Toggle Outside Fault</button>
         </div>
 
-        <h2>Alarm Settings</h2>
-        <div class="settings-list">
-            <label>
-                Rear Seat Warning °F
-                <input id="rearWarningInput" type="number" value="85">
-            </label>
-
-            <label>
-                Rear Seat Critical °F
-                <input id="rearCriticalInput" type="number" value="95">
-            </label>
-
-            <label>
-                Fridge Zone 1 Warm °F
-                <input id="fridgeZone1WarmInput" type="number" value="45">
-            </label>
-
-            <label>
-                Fridge Zone 2 Warm °F
-                <input id="fridgeZone2WarmInput" type="number" value="15">
-            </label>
-
-            <label>
-                Battery Low %
-                <input id="batteryLowInput" type="number" value="20">
-            </label>
-
-            <button onclick="saveAlarmSettings()">Save Alarm Settings</button>
-        </div>
     </section>
 </main>
 
@@ -136,6 +119,7 @@
     <button onclick="showScreen('temps')">Temps</button>
     <button onclick="showScreen('power')">Power</button>
     <button onclick="showScreen('system')">System</button>
+    <button onclick="showScreen('config')">Config</button>
 </nav>
 
 <script>
@@ -149,7 +133,8 @@ let alarmConfig = {
     rear_seat_critical: 95,
     fridge_zone_1_warm: 45,
     fridge_zone_2_warm: 15,
-    battery_low: 20
+    battery_low: 20,
+    audible_alarms: true
 };
 
 function showScreen(id) {
@@ -186,7 +171,11 @@ function checkAlarms(data) {
     const alarms = [];
     const warnings = [];
 
-    for (const [name, healthy] of Object.entries(data.sensor_health)) {
+    if (data.network.communication_lost) {
+        warnings.push('Communication lost: RS-485 disconnected');
+    }
+
+    for (const [name, healthy] of Object.entries(data.sensor_health || {})) {
         if (!healthy) {
             warnings.push(`Sensor fault: ${name.replaceAll('_', ' ')}`);
         }
@@ -232,6 +221,10 @@ function checkAlarms(data) {
 
 function showAlarm(alarm) {
     activeAlarmKey = alarm.key;
+
+    if (alarmConfig.audible_alarms) {
+        console.log('BEEP BEEP BEEP - alarm sound placeholder');
+    }
     document.getElementById('alarmTitle').textContent = alarm.title;
     document.getElementById('alarmMessage').textContent = alarm.message;
     document.getElementById('alarmOverlay').classList.remove('hidden');
@@ -265,6 +258,7 @@ function loadAlarmSettings() {
     document.getElementById('fridgeZone1WarmInput').value = alarmConfig.fridge_zone_1_warm;
     document.getElementById('fridgeZone2WarmInput').value = alarmConfig.fridge_zone_2_warm;
     document.getElementById('batteryLowInput').value = alarmConfig.battery_low;
+    document.getElementById('audibleAlarmsInput').checked = alarmConfig.audible_alarms;
 }
 
 function saveAlarmSettings() {
@@ -273,7 +267,8 @@ function saveAlarmSettings() {
         rear_seat_critical: Number(document.getElementById('rearCriticalInput').value),
         fridge_zone_1_warm: Number(document.getElementById('fridgeZone1WarmInput').value),
         fridge_zone_2_warm: Number(document.getElementById('fridgeZone2WarmInput').value),
-        battery_low: Number(document.getElementById('batteryLowInput').value)
+        battery_low: Number(document.getElementById('batteryLowInput').value),
+        audible_alarms: document.getElementById('audibleAlarmsInput').checked
     };
 
     localStorage.setItem('alarmConfig', JSON.stringify(alarmConfig));
@@ -291,16 +286,22 @@ async function loadStatus() {
     document.getElementById('statusLine').textContent =
         `RS-485: ${data.network.rs485_connected ? 'Connected' : 'Lost'} | WiFi: ${data.network.wifi_enabled ? 'Enabled' : 'Disabled'}`;
 
-    document.getElementById('dashSoc').textContent = data.battery.soc;
-    document.getElementById('dashRuntime').textContent = data.battery.runtime_hours;
+    if (data.network.communication_lost) {
+        document.body.classList.add('comms-lost');
+    } else {
+        document.body.classList.remove('comms-lost');
+    }
+
+    document.getElementById('dashSoc').textContent = data.battery.soc ?? '--';
+    document.getElementById('dashRuntime').textContent = data.battery.runtime_hours ?? '--';
     document.getElementById('dashFridge1').textContent = tempText(data.temps.fridge_zone_1);
     document.getElementById('dashFridge2').textContent = tempText(data.temps.fridge_zone_2);
     document.getElementById('dashRear').textContent = tempText(data.temps.rear_seat);
 
-    setSensorCard('cardFridge1', 'healthFridge1', data.sensor_health.fridge_zone_1);
-    setSensorCard('cardFridge2', 'healthFridge2', data.sensor_health.fridge_zone_2);
-    setSensorCard('cardRear', 'kidStatus', data.sensor_health.rear_seat);
-    setSensorCard('cardOutside', 'healthOutside', data.sensor_health.outside);
+    setSensorCard('cardFridge1', 'healthFridge1', data.sensor_health?.fridge_zone_1 ?? true);
+    setSensorCard('cardFridge2', 'healthFridge2', data.sensor_health?.fridge_zone_2 ?? true);
+    setSensorCard('cardRear', 'kidStatus', data.sensor_health?.rear_seat ?? true);
+    setSensorCard('cardOutside', 'healthOutside', data.sensor_health?.outside ?? true);
 
     const kidStatus = document.getElementById('kidStatus');
     if (data.sensor_health.rear_seat && data.temps.rear_seat >= alarmConfig.rear_seat_critical) {
@@ -315,11 +316,11 @@ async function loadStatus() {
     document.getElementById('dashFridgeRelay').textContent = `Fridge: ${onOff(data.relays.fridge)}`;
 
     document.getElementById('batSoc').textContent = data.battery.soc;
-    document.getElementById('batVoltage').textContent = data.battery.voltage;
-    document.getElementById('batCurrent').textContent = data.battery.current;
-    document.getElementById('batRemaining').textContent = data.battery.remaining_ah;
-    document.getElementById('batRuntime').textContent = data.battery.runtime_hours;
-    document.getElementById('batTemp').textContent = data.battery.temperature_f;
+    document.getElementById('batVoltage').textContent = data.battery.voltage ?? '--';
+    document.getElementById('batCurrent').textContent = data.battery.current ?? '--';
+    document.getElementById('batRemaining').textContent = data.battery.remaining_ah ?? '--';
+    document.getElementById('batRuntime').textContent = data.battery.runtime_hours ?? '--';
+    document.getElementById('batTemp').textContent = data.battery.temperature_f ?? '--';
 
     document.getElementById('tempFridge1').textContent = tempText(data.temps.fridge_zone_1);
     document.getElementById('tempFridge2').textContent = tempText(data.temps.fridge_zone_2);
@@ -332,8 +333,17 @@ async function loadStatus() {
     document.getElementById('sysRs485').textContent = data.network.rs485_connected ? 'Connected' : 'Disconnected';
     document.getElementById('sysWifi').textContent = data.network.wifi_enabled ? 'Enabled' : 'Disabled';
     document.getElementById('sysWifiOverride').textContent = data.network.wifi_override_active ? 'Active' : 'Inactive';
-    document.getElementById('sysIgnition').textContent = data.vehicle.ignition_on ? 'ON' : 'OFF';
-    updateSleepOverlay(data.vehicle.ignition_on);
+    document.getElementById('sysIgnition').textContent = data.vehicle?.ignition_on ? 'ON' : 'OFF';
+
+    document.getElementById('commsPrimary').textContent = data.network.rs485_connected ? 'RS-485' : 'RS-485 LOST';
+    document.getElementById('commsBackup').textContent = 'WiFi';
+    document.getElementById('commsSent').textContent = data.network.messages_sent ?? '--';
+    document.getElementById('commsReceived').textContent = data.network.messages_received ?? '--';
+    document.getElementById('commsLast').textContent = data.network.last_message_time
+        ? new Date(data.network.last_message_time * 1000).toLocaleTimeString()
+        : '--';
+
+    updateSleepOverlay(data.vehicle?.ignition_on ?? true);
 
     checkAlarms(data);
 }
@@ -385,6 +395,26 @@ async function toggleIgnition() {
     loadStatus();
 }
 
+async function disconnectRs485() {
+    await fetch('/comms/rs485/disconnect', {
+        method: 'POST',
+        headers: {'Content-Type': 'application/json'},
+        body: JSON.stringify({})
+    });
+
+    loadStatus();
+}
+
+async function restoreRs485() {
+    await fetch('/comms/rs485/restore', {
+        method: 'POST',
+        headers: {'Content-Type': 'application/json'},
+        body: JSON.stringify({})
+    });
+
+    loadStatus();
+}
+
 async function toggleSensorFault(name) {
     await fetch(`/sensor/${name}/fault`, {
         method: 'POST',