diff --git a/src/data/__init__.py b/src/data/__init__.py
index 02eb0e3..d09a2ed 100644
--- a/src/data/__init__.py
+++ b/src/data/__init__.py
@@ -64,10 +64,12 @@ def _save_overrides(fname: str, overrides: list):
         json.dump(overrides, file, indent=2)
 
 
-def get_controller(port: int) -> dict:
+def get_controller(port: int, model: str) -> dict:
     controllers = get_controllers()
     models = get_controller_types()
-    controller = next(filter(lambda x: x['Port'] == port, controllers), None)
+    controller = next(
+        filter(lambda x: x['Port'] == port and x['Type'] == model,
+               controllers), None)
     if not controller:
         return None
     model = next(filter(lambda x: x['Name'] == controller['Type'], models),
@@ -76,12 +78,13 @@ def get_controller(port: int) -> dict:
     return controller
 
 
-def get_controller_registers(port: int) -> list:
+def get_controller_registers(port: int, model_name: str) -> list:
     result = []
-    controller = get_controller(port)
+    controller = get_controller(port, model_name)
     for reg in controller['Model']['Registers']:
         reg['CurrentValue'] = _get_reg_value(controller, reg)
         result.append(reg)
+    result = sorted(result, key=lambda x: x['Address'])
     return result
 
 
@@ -112,6 +115,7 @@ def set_controller_register(ct: str, port: int, reg: str, val):
 
 
 def get_controllers() -> dict:
+    """Returns controllers along with their type represented as 'Model'."""
     with open(_get_controlers_fname(), 'r') as file:
         try:
             controllers = json.load(file)
@@ -133,9 +137,15 @@ def set_controllers(data: list):
 
 
 def get_controller_types() -> dict:
+    """Returns controller types as they are in the json file."""
     with open(_get_controller_models_fname(), 'r') as file:
         try:
             models = json.load(file)
+            for m in models:
+                registers = m.get('Registers', [])
+                for r in registers:
+                    if 'Function' not in r:
+                        r['Function'] = 'F16'
         except (json.JSONDecodeError):
             models = []
     return models
diff --git a/src/data/controller-models.json b/src/data/controller-models.json
index 08b7f22..08b3f59 100644
--- a/src/data/controller-models.json
+++ b/src/data/controller-models.json
@@ -1,91 +1,53 @@
 [
+  {
+    "Name": "ThirdPartyInput",
+    "RunAs": "Client-script",
+    "Script": "import time\r\nt = int(time.time() * 1000)\r\ncounter = 0\r\nchunks = []\r\nchunks.append(2)\r\nchunks.append(counter)\r\nchunks.append((t >> 48))\r\nchunks.append((t >> 32) & 0xFFFF)\r\nchunks.append((t >> 16) & 0xFFFF)\r\nchunks.append(t & 0xFFFF)\r\nchunks.append(128)\r\nchunks.append(5)\r\nchunks.append(65)\r\ninstance.write_multiple_registers(505, chunks)",
+    "ScriptExample": "import time\r\nt = int(time.time() * 1000)\r\ncounter = 0\r\nchunks = []\r\nchunks.append(2)\r\nchunks.append(counter)\r\nchunks.append((t >> 48))\r\nchunks.append((t >> 32) & 0xFFFF)\r\nchunks.append((t >> 16) & 0xFFFF)\r\nchunks.append(t & 0xFFFF)\r\nchunks.append(129)\r\nchunks.append(1)\r\nchunks.append(65)\r\ninstance.write_multiple_registers(505, chunks)"
+  },
   {
     "Name": "Ads",
     "RunAs": "Client",
     "Registers": [
       {
         "CanOverride": false,
-        "Name": "Status2",
-        "Type": "Input",
+        "Name": "Status",
+        "Type": "Holding",
+        "Function": "F3",
         "Address": 0,
         "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
-            "NotOperting": 0
+            "Oki": 1
           },
           {
-            "Operating": 1
+            "Error": 0
           }
         ]
       },
       {
         "CanOverride": false,
-        "Name": "Sim160",
+        "Name": "LastExposedTurbine",
         "Type": "Input",
+        "Function": "F4",
         "Address": 928,
         "DisplayAs": "RawBinary",
         "PossibleValues": []
       },
       {
         "CanOverride": false,
-        "Name": "ConfigUnixTime4",
-        "Type": "Input",
-        "Address": 259,
-        "DisplayAs": "RawBinary",
-        "PossibleValues": []
-      },
-      {
-        "CanOverride": false,
-        "Name": "ConfigUnixTime3",
-        "Type": "Input",
-        "Address": 258,
-        "DisplayAs": "RawBinary",
-        "PossibleValues": []
-      },
-      {
-        "CanOverride": false,
-        "Name": "ConfigUnixTime2",
-        "Type": "Input",
-        "Address": 257,
-        "DisplayAs": "RawBinary",
-        "PossibleValues": []
-      },
-      {
-        "CanOverride": false,
-        "Name": "ConfigUnixTime1",
-        "Type": "Input",
-        "Address": 256,
-        "DisplayAs": "RawBinary",
-        "PossibleValues": []
-      },
-      {
-        "CanOverride": false,
-        "Name": "TurbinesConfigured",
-        "Type": "Input",
-        "Address": 261,
-        "DisplayAs": "RawBinary",
-        "PossibleValues": []
-      },
-      {
-        "CanOverride": false,
-        "Name": "InterfaceVersion",
-        "Type": "Input",
-        "Address": 260,
-        "DisplayAs": "RawBinary",
-        "PossibleValues": []
-      },
-      {
-        "CanOverride": false,
-        "Name": "Sim2",
+        "Name": "SecondExposedTurbine",
         "Type": "Input",
+        "Function": "F4",
         "Address": 770,
         "DisplayAs": "RawBinary",
         "PossibleValues": []
       },
       {
         "CanOverride": false,
-        "Name": "Sim1",
+        "Name": "FirstExposedTurbine",
         "Type": "Input",
+        "Function": "F4",
         "Address": 769,
         "DisplayAs": "RawBinary",
         "PossibleValues": []
@@ -94,32 +56,72 @@
         "CanOverride": false,
         "Name": "SystemStatusCode",
         "Type": "Input",
+        "Function": "F4",
         "Address": 1,
         "DisplayAs": "RawBinary",
         "PossibleValues": []
       },
       {
-        "CanOverride": true,
-        "Name": "Interface",
-        "Type": "Holding",
-        "Address": 512,
-        "PossibleValues": [
-          {
-            "Deactivated": 0
-          },
-          {
-            "AircraftDetected": 1
-          },
-          {
-            "AircraftNotDetected": 3
-          }
-        ]
+        "CanOverride": false,
+        "Name": "InterfaceVersion",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 260,
+        "DisplayAs": "RawBinary",
+        "PossibleValues": []
       },
       {
         "CanOverride": false,
-        "Name": "Status",
-        "Type": "Holding",
+        "Name": "TurbinesConfigured",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 261,
+        "DisplayAs": "RawBinary",
+        "PossibleValues": []
+      },
+      {
+        "CanOverride": false,
+        "Name": "ConfigUnixTime1",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 256,
+        "DisplayAs": "RawBinary",
+        "PossibleValues": []
+      },
+      {
+        "CanOverride": false,
+        "Name": "ConfigUnixTime2",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 257,
+        "DisplayAs": "RawBinary",
+        "PossibleValues": []
+      },
+      {
+        "CanOverride": false,
+        "Name": "ConfigUnixTime3",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 258,
+        "DisplayAs": "RawBinary",
+        "PossibleValues": []
+      },
+      {
+        "CanOverride": false,
+        "Name": "ConfigUnixTime4",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 259,
+        "DisplayAs": "RawBinary",
+        "PossibleValues": []
+      },
+      {
+        "CanOverride": false,
+        "Name": "Status2",
+        "Type": "Input",
+        "Function": "F4",
         "Address": 0,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "NotOperting": 0
@@ -134,6 +136,16 @@
       "DropdownVariants",
       "RawBinary",
       "RawInteger"
+    ],
+    "Functions": [
+      "F1",
+      "F2",
+      "F3",
+      "F4",
+      "F5",
+      "F6",
+      "F15",
+      "F16"
     ]
   },
   {
@@ -142,40 +154,33 @@
     "Registers": [
       {
         "CanOverride": true,
-        "Name": "RemoteReset",
-        "Type": "Coil",
-        "Address": 20001,
+        "Name": "PhotecellSensing",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 20202,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
-            "NoReset": 0
+            "Night": 1
           },
           {
-            "Reset": 1
-          }
-        ]
-      },
-      {
-        "CanOverride": false,
-        "Name": "ForcedOffAdls",
-        "Type": "Holding",
-        "Address": 20210,
-        "PossibleValues": [
-          {
-            "Auto": 0
+            "Twilight": 2
           },
           {
-            "AircraftNotDetected": 128
+            "Day": 3
           },
           {
-            "AircraftDetected": 129
+            "FailSafeIntensity": 255
           }
         ]
       },
       {
         "CanOverride": true,
-        "Name": "Status",
+        "Name": "FullSystemStatus",
         "Type": "Input",
+        "Function": "F4",
         "Address": 19000,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "Normal": 1
@@ -188,6 +193,9 @@
           },
           {
             "FailAndAlarm": 4
+          },
+          {
+            "BAD": 666
           }
         ]
       },
@@ -195,7 +203,9 @@
         "CanOverride": true,
         "Name": "TimeOfDay",
         "Type": "Input",
+        "Function": "F4",
         "Address": 20200,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "ControllerOff": 0
@@ -223,11 +233,53 @@
           }
         ]
       },
+      {
+        "CanOverride": false,
+        "Name": "ForcedOffAdls",
+        "Type": "Holding",
+        "Function": "F3",
+        "Address": 20210,
+        "DisplayAs": "DropdownVariants",
+        "PossibleValues": [
+          {
+            "Auto": 0
+          },
+          {
+            "AircraftNotDetected": 128
+          },
+          {
+            "AircraftDetected": 129
+          }
+        ]
+      }
+    ],
+    "DisplayVariants": [
+      "DropdownVariants",
+      "RawBinary",
+      "RawInteger"
+    ],
+    "Functions": [
+      "F1",
+      "F2",
+      "F3",
+      "F4",
+      "F5",
+      "F6",
+      "F15",
+      "F16"
+    ]
+  },
+  {
+    "Name": "CIP400",
+    "RunAs": "Server",
+    "Registers": [
       {
         "CanOverride": true,
-        "Name": "OverallSystemStatus",
+        "Name": "SelfStatus",
         "Type": "Input",
+        "Function": "F4",
         "Address": 19005,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "Normal": 1
@@ -242,18 +294,14 @@
             "FailAndAlarm": 4
           }
         ]
-      }
-    ]
-  },
-  {
-    "Name": "CIP400",
-    "RunAs": "Server",
-    "Registers": [
+      },
       {
         "CanOverride": true,
         "Name": "RemoteReset",
         "Type": "Coil",
+        "Function": "F5",
         "Address": 20001,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "NoReset": 0
@@ -263,28 +311,13 @@
           }
         ]
       },
-      {
-        "CanOverride": false,
-        "Name": "ForcedOffAdls",
-        "Type": "Holding",
-        "Address": 20210,
-        "PossibleValues": [
-          {
-            "Auto": 0
-          },
-          {
-            "AircraftNotDetected": 128
-          },
-          {
-            "AircraftDetected": 129
-          }
-        ]
-      },
       {
         "CanOverride": true,
         "Name": "Status",
         "Type": "Input",
+        "Function": "F4",
         "Address": 19000,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "Normal": 1
@@ -304,7 +337,9 @@
         "CanOverride": true,
         "Name": "TimeOfDay",
         "Type": "Input",
+        "Function": "F4",
         "Address": 20200,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "ControllerOff": 0
@@ -336,7 +371,9 @@
         "CanOverride": true,
         "Name": "PhotocellSensing",
         "Type": "Input",
+        "Function": "F4",
         "Address": 20202,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "Night": 1
@@ -353,25 +390,39 @@
         ]
       },
       {
-        "CanOverride": true,
-        "Name": "OverallSystemStatus",
-        "Type": "Input",
-        "Address": 19005,
+        "CanOverride": false,
+        "Name": "ForcedOffAdls",
+        "Type": "Holding",
+        "Function": "F6",
+        "Address": 20210,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
-            "Normal": 1
+            "Auto": 0
           },
           {
-            "Fail": 2
+            "AircraftNotDetected": 128
           },
           {
-            "Alarm": 3
-          },
-          {
-            "FailAndAlarm": 4
+            "AircraftDetected": 129
           }
         ]
       }
+    ],
+    "DisplayVariants": [
+      "DropdownVariants",
+      "RawBinary",
+      "RawInteger"
+    ],
+    "Functions": [
+      "F1",
+      "F2",
+      "F3",
+      "F4",
+      "F5",
+      "F6",
+      "F15",
+      "F16"
     ]
   },
   {
@@ -380,9 +431,30 @@
     "Registers": [
       {
         "CanOverride": false,
-        "Name": "ForcedOffAdls",
+        "Name": "ForcedOffAdlsWrite",
         "Type": "Holding",
+        "Function": "F6",
         "Address": 512,
+        "DisplayAs": "DropdownVariants",
+        "PossibleValues": [
+          {
+            "Auto": 0
+          },
+          {
+            "AircraftDetected": 1
+          },
+          {
+            "AircraftNotDetected": 3
+          }
+        ]
+      },
+      {
+        "CanOverride": true,
+        "Name": "ForcedOffAdlsRead",
+        "Type": "Input",
+        "Function": "F4",
+        "Address": 512,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "Auto": 0
@@ -399,7 +471,9 @@
         "CanOverride": true,
         "Name": "OverallSystemStatus",
         "Type": "Input",
+        "Function": "F4",
         "Address": 0,
+        "DisplayAs": "DropdownVariants",
         "PossibleValues": [
           {
             "NotOperting": 0
@@ -409,6 +483,21 @@
           }
         ]
       }
+    ],
+    "DisplayVariants": [
+      "DropdownVariants",
+      "RawBinary",
+      "RawInteger"
+    ],
+    "Functions": [
+      "F1",
+      "F2",
+      "F3",
+      "F4",
+      "F5",
+      "F6",
+      "F15",
+      "F16"
     ]
   }
 ]
\ No newline at end of file
diff --git a/src/data/controllers.json b/src/data/controllers.json
index 34c8463..c2f83c5 100644
--- a/src/data/controllers.json
+++ b/src/data/controllers.json
@@ -1,10 +1,4 @@
 [
-  {
-    "Type": "Ads",
-    "Enabled": true,
-    "Ip": "127.0.0.1",
-    "Port": 2502
-  },
   {
     "Type": "CIP400",
     "Enabled": true,
@@ -15,7 +9,19 @@
     "Type": "Quantec",
     "Enabled": true,
     "Ip": "127.0.0.1",
-    "Port": 11700
+    "Port": 11704
+  },
+  {
+    "Type": "ThirdPartyInput",
+    "Enabled": true,
+    "Ip": "127.0.0.1",
+    "Port": 2502
+  },
+  {
+    "Type": "Ads",
+    "Enabled": true,
+    "Ip": "127.0.0.1",
+    "Port": 2502
   },
   {
     "Type": "CIP300",
@@ -24,9 +30,9 @@
     "Port": 11508
   },
   {
-    "Type": "CIP400",
+    "Type": "Quantec",
     "Enabled": true,
     "Ip": "127.0.0.1",
-    "Port": 11506
+    "Port": 11705
   }
 ]
\ No newline at end of file
diff --git a/src/modbus/simulator.py b/src/modbus/simulator.py
index 09f65dd..0ce7813 100755
--- a/src/modbus/simulator.py
+++ b/src/modbus/simulator.py
@@ -62,61 +62,120 @@ def remove_instance(instance, key: str):
     del _active[key]
 
 
-def handle_server(instance):
-    for reg in data.get_controller_registers(instance.port):
+def handle_server(instance, ct: dict):
+    for reg in data.get_controller_registers(instance.port, ct.get('Name',
+                                                                   '')):
         if not reg['CanOverride']:
             continue
         tp = reg['Type'].lower()
         v = reg['CurrentValue']
         if tp == 'input' and v is not None:
             instance.data_bank.set_input_registers(int(reg['Address']), [v])
+        if tp == 'holding' and v is not None:
+            instance.data_bank.set_holding_registers(int(reg['Address']), [v])
+
+
+def handle_client_script(instance, script: str):
+    exec(script, {}, {'instance': instance})
 
 
 def handle_client(instance, ct: dict):
-    registers = data.get_controller_registers(instance.port)
-    holdingRead = next(
-        filter(lambda x: x['Type'] == 'Holding' and x['CanOverride'] is False,
-               registers), None)
+    """ Acts as a Modbus client. Function codes matter.
 
-    holdingWrite = next(
-        filter(lambda x: x['Type'] == 'Holding' and x['CanOverride'] is True,
-               registers), None)
+    FC1 - read coils
+    FC4 - read input
+    FC3 - read holding
+    FC5 - write coils
+    FC6 - write holding """
 
-    inputRegs = filter(lambda x: x['Type'] == 'Input', registers)
+    registers = data.get_controller_registers(instance.port, ct['Name'])
+
+    inputRead = filter(lambda x: x['Function'] == 'F4', registers)
+    holdingRead = filter(lambda x: x['Function'] == 'F3', registers)
+    coilsRead = filter(lambda x: x['Function'] == 'F1', registers)
+    coilsWrite = filter(lambda x: x['Function'] == 'F5', registers)
+    holdingWrite = filter(lambda x: x['Function'] == 'F6', registers)
 
     regs = {}
     for r in registers:
         regs[r['Address']] = r['Name']
     info = {'Model': ct['Name'], 'Port': instance.port, 'Registers': regs}
 
-    if holdingRead:
-        result = instance.read_holding_registers(holdingRead['Address'], 1)
-        if result is None:
-            logging.debug(f'{ct["Name"]} client@{instance.port} no connection')
-        else:
-            gather('read', 'holding', holdingRead['Address'], instance.port,
-                   result[0], info, 'outbound')
+    warn = '{0} register {1} on server {2} is misconfigured. {3} call result is {4}'
+    connected = False
+
+    # Input read
+    for r in list(inputRead):
+        result = instance.read_input_registers(r['Address'])
+        if result is not None:
+            gather('read', 'input', r['Address'], instance.port, result[0],
+                   info, 'outbound')
             data.set_controller_register(info['Model'], info['Port'],
-                                         holdingRead['Name'], result[0])
-            if holdingWrite:
-                v = holdingWrite['CurrentValue']
-                instance.write_single_register(holdingWrite['Address'], v)
-                gather('write', 'holding', holdingWrite['Address'],
-                       instance.port, v, info, 'outbound')
-            for r in list(inputRegs):
-                result = instance.read_input_registers(r['Address'])
-                if result is not None:
-                    gather('read', 'input', r['Address'], instance.port,
-                           result[0], info, 'outbound')
-                    data.set_controller_register(info['Model'], info['Port'],
-                                                 r['Name'], result[0])
-                else:
-                    logging.warning(
-                        f'Input register {r["Name"]} on server {instance.port} is misconfigured. Read result is None'
-                    )
-    else:
-        logging.warning(
-            f'{ct["Name"]} client@{instance.port} is not fully configured')
+                                         r['Name'], result[0])
+            connected = True
+        else:
+            logging.debug(
+                warn.format('Input', r['Name'], instance.port, 'FC4', result))
+            break
+
+    # Holding read
+    for r in list(holdingRead):
+        result = instance.read_holding_registers(r['Address'])
+        if result is not None:
+            gather('read', 'holding', r['Address'], instance.port, result[0],
+                   info, 'outbound')
+            data.set_controller_register(info['Model'], info['Port'],
+                                         r['Name'], result[0])
+            connected = True
+        else:
+            logging.debug(
+                warn.format('Holding', r['Name'], instance.port, 'FC3',
+                            result))
+            break
+
+    # Coils read
+    for r in list(coilsRead):
+        result = instance.read_coils(r['Address'])
+        if result is not None:
+            gather('read', 'coils', r['Address'], instance.port, result[0],
+                   info, 'outbound')
+            data.set_controller_register(info['Model'], info['Port'],
+                                         r['Name'], result[0])
+            connected = True
+        else:
+            logging.debug(
+                warn.format('Coils', r['Name'], instance.port, 'FC1', result))
+            break
+
+    # Coils write
+    for r in list(coilsWrite):
+        result = instance.write_single_coil(r['Address'],
+                                            r.get('CurrentValue', False))
+        if result is True:
+            gather('write', 'coils', r['Address'], instance.port,
+                   r.get('CurrentValue', False), info, 'outbound')
+            connected = True
+        else:
+            logging.debug(
+                warn.format('Coils', r['Name'], instance.port, 'FC5', result))
+            break
+
+    # Holding write
+    for r in list(holdingWrite):
+        result = instance.write_single_register(r['Address'],
+                                                r.get('CurrentValue', 0))
+        if result is True:
+            gather('write', 'holding', r['Address'], instance.port,
+                   r.get('CurrentValue', 0), info, 'outbound')
+            connected = True
+        else:
+            logging.debug(
+                warn.format('Holding', r['Name'], instance.port, 'FC6',
+                            result))
+            break
+
+    if not connected:
+        logging.debug(f'{ct["Name"]} client@{instance.port} no connection')
 
 
 def add_new(controllers: list):
@@ -297,9 +356,6 @@ def merge_dict(base: dict, incoming: dict) -> dict:
 def aggregate_freq(collection: dict):
     for k, v in collection.items():
         del v[0]
-        # print(f'{k}:')
-        # for timestamp, freq in v.items():
-        #     print(f'{timestamp} {freq} ')
     merged = {}
     for k, v in collection.items():
         merged = merge_dict(merged, v)
@@ -446,7 +502,7 @@ if __name__ == '__main__':
             for k in list(_active.keys()):
                 instance = _active[k]['instance']
                 c = next(
-                    filter(lambda c: instance.port == int(c['Port']),
+                    filter(lambda x: f"{x['Type']}@{x['Port']}" == k,
                            controllers), None)
 
                 if not c or not c['Enabled']:
@@ -454,9 +510,12 @@ if __name__ == '__main__':
                     continue
 
                 if type(instance) is ModbusServer:
-                    handle_server(instance)
+                    handle_server(instance, c['Model'])
                 else:
-                    handle_client(instance, c['Model'])
+                    if c['Model']['RunAs'] == 'Client-script':
+                        handle_client_script(instance, c['Model']['Script'])
+                    else:
+                        handle_client(instance, c['Model'])
             sleep(5)
             calculate_freq(5, datetime.datetime.now())
 
diff --git a/src/ui/controller_types.py b/src/ui/controller_types.py
index 876a0ce..3d424ab 100644
--- a/src/ui/controller_types.py
+++ b/src/ui/controller_types.py
@@ -61,6 +61,11 @@ def edit(name: str):
                 _save_model(existing, name)
                 existing = _prepare_for_editing(name)
                 break
+            elif key.startswith('script_'):
+                existing['Script'] = request.form['script']
+                _save_model(existing, name)
+                existing = _prepare_for_editing(name)
+                break
             elif key.startswith('rename_'):
                 _abort_if_cannot_delete(name)
                 existing['Name'] = request.form['name']
@@ -98,11 +103,14 @@ def _find_model_by_name(name: str, models: dict = None) -> dict:
 
 
 def _prepare_for_editing(name: str):
+    functions = ['F1', 'F2', 'F3', 'F4', 'F5', 'F6', 'F15', 'F16']
     types = ['Input', 'Holding', 'Coil', 'Discrete']
     variants = ['DropdownVariants', 'RawBinary', 'RawInteger']
     exists = _find_model_by_name(name)
     if not exists:
         return None
+    if exists['RunAs'] == 'Client-script':
+        return exists
     for reg in exists['Registers']:
         processed = []
         for possible in reg['PossibleValues']:
@@ -111,19 +119,21 @@ def _prepare_for_editing(name: str):
         reg['PossibleValues'] = '\n'.join(processed)
     exists['RegTypes'] = types
     exists['DisplayVariants'] = variants
+    exists['Functions'] = functions
     return exists
 
 
 def _save_model(model: dict, current_name: str):
     models = data.get_controller_types()
     models = [x for x in models if x['Name'] != current_name]
-    del model['RegTypes']
-    _remove_reg(model, '')
-    for r in model['Registers']:
-        if 'PossibleValues' in r:
-            r['PossibleValues'] = _str_to_possible(r['PossibleValues'])
-        else:
-            r['PossibleValues'] = []
+    if model['RunAs'] != 'Client-script':
+        del model['RegTypes']
+        _remove_reg(model, '')
+        for r in model['Registers']:
+            if 'PossibleValues' in r:
+                r['PossibleValues'] = _str_to_possible(r['PossibleValues'])
+            else:
+                r['PossibleValues'] = []
     models.insert(0, model)
     data.set_controller_types(models)
 
@@ -156,6 +166,8 @@ def _update_reg(model: dict, reg_name: str, form: dict):
             updated['CanOverride'] = v == 'True'
         elif k == f'{reg_name}-type':
             updated['Type'] = v
+        elif k == f'{reg_name}-function':
+            updated['Function'] = v
         elif k == f'{reg_name}-display-as':
             updated['DisplayAs'] = v
         elif k == f'{reg_name}-possible':
diff --git a/src/ui/controllers.py b/src/ui/controllers.py
index d139266..5a100a8 100644
--- a/src/ui/controllers.py
+++ b/src/ui/controllers.py
@@ -37,17 +37,21 @@ def update():
     if existing is None:
         abort(404)
 
-    current_regs = data.get_controller_registers(existing['Port'])
-    for r in registers:
-        reg = next(filter(lambda x: x['Name'] == r['Name'], current_regs), r)
-        display_as = reg.get('DisplayAs', 'DropdownVariants')
-        if display_as == 'RawBinary' and _is_binary_str(r['Value']):
-            r['Value'] = int(r['Value'], 2)
-        else:
-            r['Value'] = int(r['Value'])
+    if existing['Model']['RunAs'] != 'Client-script':
 
-    data.set_controller_registers(existing['Type'], existing['Port'],
-                                  registers)
+        current_regs = data.get_controller_registers(existing['Port'],
+                                                     existing['Type'])
+        for r in registers:
+            reg = next(filter(lambda x: x['Name'] == r['Name'], current_regs),
+                       r)
+            display_as = reg.get('DisplayAs', 'DropdownVariants')
+            if display_as == 'RawBinary' and _is_binary_str(r['Value']):
+                r['Value'] = int(r['Value'], 2)
+            else:
+                r['Value'] = int(r['Value'])
+
+        data.set_controller_registers(existing['Type'], existing['Port'],
+                                      registers)
     enabled = enabled == 'True'
 
     if existing['Enabled'] != enabled:
@@ -87,7 +91,7 @@ def add():
         controller = _find(p, controllers)
         if p < 1024 or p > 65536:
             flash('Port should be in range 1025-65536')
-        elif controller:
+        elif controller and controller['Model']['RunAs'] == 'Server':
             flash('This port is already assigned to another controller!')
         elif t not in types:
             flash(f'Type {t} was not found')
@@ -134,27 +138,31 @@ def get_list() -> dict:
     for controller in controllers:
         controller['Enabled'] = _to_status(controller['Enabled'])
         controller['Registers'] = []
-        registers = data.get_controller_registers(controller['Port'])
+        if controller['Model']['RunAs'] != 'Client-script':
+            registers = data.get_controller_registers(controller['Port'],
+                                                      controller['Type'])
 
-        for reg in registers:
-            controller['Registers'].append({
-                'Name':
-                reg['Name'],
-                'Value':
-                _get_current_value(reg),
-                'ValueStr':
-                _get_value_name(reg),
-                'Address':
-                reg['Address'],
-                'Type':
-                reg['Type'],
-                'PossibleValues':
-                reg['PossibleValues'],
-                'CanOverride':
-                reg['CanOverride'],
-                'DisplayAs':
-                reg.get('DisplayAs', 'DropdownVariants')
-            })
+            for reg in registers:
+                controller['Registers'].append({
+                    'Name':
+                    reg['Name'],
+                    'Value':
+                    _get_current_value(reg),
+                    'ValueStr':
+                    _get_value_name(reg),
+                    'Address':
+                    reg['Address'],
+                    'Type':
+                    reg['Type'],
+                    'PossibleValues':
+                    reg['PossibleValues'],
+                    'CanOverride':
+                    reg['CanOverride'],
+                    'DisplayAs':
+                    reg.get('DisplayAs', 'DropdownVariants'),
+                    'Function':
+                    reg['Function']
+                })
 
     return controllers
 
diff --git a/src/ui/templates/controller_types/create.html b/src/ui/templates/controller_types/create.html
index ecd3acf..42d4f51 100644
--- a/src/ui/templates/controller_types/create.html
+++ b/src/ui/templates/controller_types/create.html
@@ -16,6 +16,7 @@
       <div><select id="runAs" name="runAs">
       <option value="Server">Server</option>
       <option value="Client">Client</option>
+      <option value="Client-script">Client-script</option>
       </select></div>
     </div>
 <br/>
diff --git a/src/ui/templates/controller_types/list.html b/src/ui/templates/controller_types/list.html
index 18b8e83..231fef0 100644
--- a/src/ui/templates/controller_types/list.html
+++ b/src/ui/templates/controller_types/list.html
@@ -14,7 +14,16 @@
         <a class="button" href="{{ url_for('controller_types.copy', name=type['Name']) }}">Copy</a>
         <a class="delete" href="{{ url_for('controller_types.delete', name=type['Name']) }}">Delete</a>
 
-     {% for reg in type['Registers'] %}
+
+        {% if type['RunAs']== 'Client-script' %}
+
+        <p>
+        <div><label>Script to be executed:</label></div>
+        <div><textarea rows="16" cols="64" disabled> {{ type['Script'] }} </textarea></div>
+        </p>
+        {% endif %}
+
+        {% for reg in type['Registers'] %}
 
       <div class="setting-wide">
         <div><label for="reg-{{ reg['Name'] }}">{{ reg['Type'] }} {{ reg['Address'] }} ({{ reg['Name'] }}):</label></div>
@@ -30,10 +39,12 @@
           {% endfor %}
           {% endfor %}
       </select>
+      <div class="grey-box">{{ reg['Function'] }}</div>
 
       {% else %}
 
       <div class="grey-box">{{ reg['DisplayAs'] }}</div>
+      <div class="grey-box">{{ reg['Function'] }}</div>
 
       {% endif %}
       </div>
diff --git a/src/ui/templates/controller_types/update.html b/src/ui/templates/controller_types/update.html
index 4d394a9..56e10af 100644
--- a/src/ui/templates/controller_types/update.html
+++ b/src/ui/templates/controller_types/update.html
@@ -18,7 +18,33 @@
       <button class="button rename" type="submit" name="rename_{{ data['Name'] }}">Rename</button>
       </section>
     </div>
-<br/>
+    <br/>
+
+    {% if data['RunAs'] == 'Client-script' %}
+    <section>
+      <section class="row">
+        <div><button class="button" type="submit" name="script_update">Save</button></div>
+      </section>
+
+      <section class="row">
+        <p>Example of a script. `instance` object is available and represents MODBUS client that can be used for reading or writing registers</p>
+      </section>
+
+      <section class="row">
+      <div>
+        <textarea name="script" rows="16" cols="64" disabled>{{ data['ScriptExample'] }}</textarea>
+      </div>
+      </section>
+
+    <section>
+      <div><label for="script">Script to be run:</label></div>
+      <div><textarea name="script" rows="16" cols="64" placeholder="ValueNameOne=14&#13;ValueNameTwo=3" required>{{ request.form['script'] or data['Script'] }}</textarea></div>
+    </section>
+
+    </section>
+
+
+    {% else %}
 
     <div><button class="button" type="submit" name="add_register">Add Register</button></div>
     <section class="container">
@@ -55,6 +81,15 @@
            <option value="{{ option }}" {% if option == reg['Type'] %}selected{% endif %}>{{ option }}</option>
            {% endfor %}
       </select></div>
+     </div>
+
+     <div>
+       <div><label for="{{ reg['Name'] }}-function">Function:</label></div>
+       <div><select id="{{ reg['Name'] }}-function" name="{{ reg['Name'] }}-function">
+           {% for option in data['Functions'] %}
+           <option value="{{ option }}" {% if option == reg['Function'] %}selected{% endif %}>{{ option }}</option>
+           {% endfor %}
+      </select></div>
     </div>
 
     <div>
@@ -76,5 +111,6 @@
       </article>
     {% endfor %}
     </section>
+    {% endif %}
   </form>
 {% endblock %}
diff --git a/src/ui/templates/controllers/index.html b/src/ui/templates/controllers/index.html
index 575c912..8d94d77 100644
--- a/src/ui/templates/controllers/index.html
+++ b/src/ui/templates/controllers/index.html
@@ -21,6 +21,9 @@
         <div>{{ controller['Enabled'] }}</div>
       </div>
 
+      {% if controller['Type'] == 'Client-script' %}
+      <div>Code is going to be here</div>
+      {% else %}
       {% for reg in controller['Registers'] %}
 
       <div class="setting">
@@ -30,6 +33,7 @@
       </div>
 
       {% endfor %}
+      {% endif %}
 
       <div class="override">
         <h4>Manual override</h4>
@@ -50,6 +54,7 @@
         </div>
 
         {% for reg in controller['Registers'] %}
+
         {% if reg['CanOverride'] %}
 
       <div class="setting-wide">
@@ -63,14 +68,17 @@
           <option value="{{ value }}" {% if value == reg['Value'] %}selected{% endif %}>{{ key }} ({{ value }})</option>
           {% endfor %}
           {% endfor %}
-         </select></div>
+           </select>
+           <div class="grey-box">{{ reg['Function'] }}</div>
+         </div>
 
          {% else %}
-         <div><input id="reg-{{ reg['Name'] }}" name="{{ reg['Name'] }}" value="{{ reg['Value'] }}" required></div>
+         <div><input id="reg-{{ reg['Name'] }}" name="{{ reg['Name'] }}" value="{{ reg['Value'] }}" required><div class="grey-box">{{ reg['Function'] }}</div></div>
          {% endif %}
       </div>
 
        {% endif %}
+
       {% endfor %}
 
       <input class="button apply" type="submit" value="Apply">