readme and fix in structured mode

readme.md

@@ -0,0 +1,81 @@
+# OPC-UA to MQTT Bridge
+
+## Installation
+
+* Take the tarball from the Release area and unpack it in the desired location on the edge device
+* The systemctl service script assumes to find the application at `/home/alarm/KROHNE/opcua2mqtt-bridge`, so it is a good idea to put it there
+* Create a configuration directory `/etc/opcua2mqtt-bridge` and place the adjusted `config.json` into it
+* Enable the service using `sudo systemctl enable /home/alarm/KROHNE/opcua2mqtt-bridge/opcua2mqtt-bridge.service`
+* Start the service using `sudo systemctl start opcua2mqtt-bridge`
+* Check the log messages using `journalctl -f`
+
+## Configuration
+
+``
+{
+    "mqtt": {
+        "broker": "172.16.2.16",
+        "port": 1883,
+        "publishTopicPrefix": "opcua"
+    },
+    "stats": {
+        "topic": "statistics",
+        "period": 60
+    },
+    "opcua": [
+        {
+            "enabled": "true",
+            "type": "flat",
+            "url": "opc.tcp://172.16.3.60:4840",
+            "name": "apl",
+            "period": 1.0,
+            "timeout": 1.0,
+            "nodes": [
+                { "ns": 0, "n": "i=345", "d": "pv" },
+                { "ns": 0, "n": "i=348", "d": "sv" },
+                { "ns": 0, "n": "i=351", "d": "tv" },
+                { "ns": 0, "n": "i=354", "d": "qv" }
+            ]
+        }
+    ]
+}
+``
+
+The configuration object consists of three parts: `mqtt`, `stats` and `opcua`.
+
+In `mqtt` the access to the broker is configuration and the prefix for the topics used by the statistics module and the actual bridge are defined.
+Besides the above shown attributes the `login` and `password` for authentication at the broker and `ca`, `cert` and `key` for TLS connections to the broker are available. `ca`, `cert` and `key` contain the filenames including complete path of the particular files.
+
+In `stats` the topic suffix and the period of statistics messages are defined. The complete suffix will be `${mqtt.publicTopicPrefix}/${stats.topic}`.
+
+The section `opcua` contains a list of OPC-UA servers to be queried. Each entry can be enabled/disabled using the attribute `enabled`. The attribute `url` obviously has the URL to connect the server, `period` is the period to repeat queries and `timeout` is the timeout when talking to a server.
+`name` identifies the particular server, it becomes part of the topic of the published MQTT messages. The attribute `type` defines whether the individual variables of an OPC-UA server shall be communicated in individual MQTT messages (`flat`) or all variables of a server in a single message (`structured`).
+
+The attribute `nodes` finally contains the list of variables to be queried. It contains the namespace index (`ns`), the node-id (`n`) and an optional descriptive name (`d`). Namespace index and node-id can be determined using for instance UAExpert when browsing the server and navigating to the relevant variables. The descriptive name - if given, otherwise the display name of the variable is used - becomes in `flat` mode part of the topic, in `structured` mode it becomes an attribute name within the message.
+
+In `flat` mode the final topic will be `${mqtt.publicTopicPrefix}/${opcua.name}/${opcua.node.ns}/${opcua.node.d}`
+
+An example for the MQTT messages according to the above configuration in `flat` mode is:
+
+``
+opcua/apl/0/pv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "pv", "value": 19.849281311035156}
+opcua/apl/0/sv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "sv", "value": 1688.5152587890625}
+opcua/apl/0/tv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "tv", "value": 22.574615478515625}
+opcua/apl/0/qv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "qv", "value": NaN}
+opcua/apl/0/pv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "pv", "value": 19.849281311035156}
+opcua/apl/0/sv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "sv", "value": 1688.5152587890625}
+opcua/apl/0/tv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "tv", "value": 22.574615478515625}
+opcua/apl/0/qv {"serverName": "apl", "nameSpaceIndex": 0, "variableName": "qv", "value": NaN}
+``
+
+In `structured` mode the final topic will be `${mqtt.publicTopicPrefix}/${opcua.name}`
+
+An example for the MQTT messages according to the above configuration in `flat` mode is:
+
+``
+opcua/apl {"pv": 19.844480514526367, "sv": 1689.9193115234375, "tv": 22.68524169921875, "qv": NaN}
+opcua/apl {"pv": 19.844480514526367, "sv": 1689.9193115234375, "tv": 22.68524169921875, "qv": NaN}
+opcua/apl {"pv": 19.844480514526367, "sv": 1689.9193115234375, "tv": 22.68524169921875, "qv": NaN}
+opcua/apl {"pv": 19.844480514526367, "sv": 1689.93701171875, "tv": 22.620391845703125, "qv": NaN}
+``
+

src/OpcUaRequester.py

@@ -17,7 +17,7 @@ class OpcUaRequester(threading.Thread):
         self.name = self.config['name']
         self.url = self.config['url']
         self.nodes = self.config['nodes']
-        self.delay = self.config['delay']
+        self.period = self.config['period']
         self.timeout = self.config['timeout']
         self.dataObjectType = self.config['type']
         self.flat = self.dataObjectType == 'flat'
@@ -49,7 +49,7 @@ class OpcUaRequester(threading.Thread):
                             logger.error(f"UaError in inner OPC-UA loop: {type(e)} {e}")
                     if not self.flat:
                         self.queue.put(dataObject)
-                await asyncio.sleep(self.delay)
+                await asyncio.sleep(self.period)
             except asyncio.exceptions.TimeoutError as e:
                 self.stats.incOpcUaTimeouts()
                 logger.error(f"Timeout in inner OPC-UA loop")

src/StructuredDataObject.py

@@ -6,10 +6,10 @@ from AbstractDataObject import AbstractDataObject
 class StructuredDataObject(AbstractDataObject):
     def __init__(self, topicPart):
         super().__init__(topicPart)
-        self.keyValuePairs = []
+        self.keyValuePairs = {}
 
     def add(self, key, value):
-        self.keyValuePairs.append({key: value})
+        self.keyValuePairs[key] =  value
 
     def getPayload(self):
         return json.dumps(self.keyValuePairs)

src/config.json

@@ -11,10 +11,10 @@
     "opcua": [
         {
             "enabled": "true",
-            "type": "flat",
+            "type": "structured",
             "url": "opc.tcp://172.16.3.60:4840",
             "name": "apl",
-            "delay": 1.0,
+            "period": 1.0,
             "timeout": 1.0,
             "nodes": [
                 { "ns": 0, "n": "i=345", "d": "pv" },
@@ -28,7 +28,7 @@
             "type": "flat",
             "url": "opc.tcp://192.168.254.5:4863",
             "name": "sh",
-            "delay": 1.0,
+            "period": 1.0,
             "timeout": 10.0,
             "nodes": [
                 { "ns": 1, "n": "s=t|SERVER::A201CD124/MOT_01.AV_Out#Value", "d": "A201CD124" },