Sensorconnect

The technical documentation of the sensorconnect microservice, which reads data from sensors and sends them to the MQTT or Kafka broker.

4 minute read

Sensorconnect automatically detects ifm gateways connected to the network and reads data from the connected IO-Link sensors.

How it works

Sensorconnect continuosly scans the given IP range for gateways, making it effectively a plug-and-play solution. Once a gateway is found, it automatically download the IODD files for the connected sensors and starts reading the data at the configured interval. Then it processes the data and sends it to the MQTT or Kafka broker, to be consumed by other microservices.

If you want to learn more about how to use sensors in your asstes, check out the retrofitting section of the UMH Learn website.

IODD files

The IODD files are used to describe the sensors connected to the gateway. They contain information about the data type, the unit of measurement, the minimum and maximum values, etc. The IODD files are downloaded automatically from IODDFinder once a sensor is found, and are stored in a Persistent Volume. If downloading from internet is not possible, for example in a closed network, you can download the IODD files manually and store them in the folder specified by the IODD_FILE_PATH environment variable.

If no IODD file is found for a sensor, the data will not be processed, but sent to the broker as-is.

Kubernetes resources

StatefulSet: united-manufacturing-hub-sensorconnect
Secret:
- Kafka: united-manufacturing-hub-sensorconnect-kafka-secrets
- MQTT: united-manufacturing-hub-sensorconnect-mqtt-secrets
PersistentVolumeClaim: united-manufacturing-hub-sensorconnect-claim

Configuration

You can configure the IP range to scan for gateways, and which message broker to use, by setting the values of the parameters in the _000_commonConfig.datasources.sensorconnect section of the Helm chart values file.

The default values of the other parameters are usually good for most use cases, but you can change them in the Danger Zone section of the Helm chart values file.

Environment variables

Environment variables
Variable name	Description	Type	Allowed values	Default
`ADDITIONAL_SLEEP_TIME_PER_ACTIVE_PORT_MS`	Additional sleep time between pollings for each active port	float	Any	0.0
`ADDITIONAL_SLOWDOWN_MAP`	JSON map of values, allows to slow down and speed up the polling time of specific sensors	JSON	See below	[]
`DEBUG_ENABLE_FGTRACE`	Enables the use of the fgtrace library. Not reccomended for production	string	true, false	false
`DEVICE_FINDER_TIMEOUT_SEC`	HTTP timeout in seconds for finding new devices	int	Any	1
`DEVICE_FINDER_TIME_SEC`	Time interval in seconds for finding new devices	int	Any	20
`IODD_FILE_PATH`	Filesystem path where to store IODD files	string	Any valid Unix path	`/ioddfiles`
`IP_RANGE`	The IP range to scan for new sensor	string	Any valid IP in CIDR notation	192.168.10.1/24
`KAFKA_BOOTSTRAP_SERVER`	URL of the Kafka broker. Port is required	string	Any	united-manufacturing-hub-kafka:9092
`KAFKA_SSL_KEY_PASSWORD`	The encrypted password of the SSL key. If empty, no password is used	string	Any	""
`LOGGING_LEVEL`	Defines which logging level is used, mostly relevant for developers	string	PRODUCTION, DEVELOPMENT	PRODUCTION
`LOWER_POLLING_TIME_MS`	Time in milliseconds to define the lower bound of time between sensor polling	int	Any	20
`MAX_SENSOR_ERROR_COUNT`	Amount of errors before a sensor is temporarily disabled	int	Any	50
`MICROSERVICE_NAME`	Name of the microservice (used for tracing)	string	Any	united-manufacturing-hub-sensorconnect
`MQTT_BROKER_URL`	URL of the MQTT broker. Port is required	string	Any	united-manufacturing-hub-mqtt:1883
`MQTT_CERTIFICATE_NAME`	Set to NO_CERT to allow non-encrypted MQTT access, or to USE_TLS to use TLS encryption	string	USE_TLS, NO_CERT	USE_TLS
`MQTT_PASSWORD`	Password for the MQTT broker	string	Any	INSECURE_INSECURE_INSECURE
`POLLING_SPEED_STEP_DOWN_MS`	Time in milliseconds subtracted from the polling interval after a successful polling	int	Any	1
`POLLING_SPEED_STEP_UP_MS`	Time in milliseconds added to the polling interval after a failed polling	int	Any	20
`SENSOR_INITIAL_POLLING_TIME_MS`	Amount of time in milliseconds before starting to request sensor data. Must be higher than `LOWER_POLLING_TIME_MS`	int	Any	100
`SUB_TWENTY_MS`	Set to 1 to allow `LOWER_POLLING_TIME_MS` of under 20 ms. This is not recommended as it might lead to the gateway becoming unresponsive until a manual reboot	int	0, 1	0
`TRANSMITTERID`	Serial number of the cluster (used for tracing)	string	Any	default
`UPPER_POLLING_TIME_MS`	Time in milliseconds to define the upper bound of time between sensor polling	int	Any	1000
`USE_KAFKA`	If enabled, uses Kafka as a message broker	string	true, false	true
`USE_MQTT`	If enabled, uses MQTT as a message broker	string	true, false	false

Slowdown map

The ADDITIONAL_SLOWDOWN_MAP environment variable allows you to slow down and speed up the polling time of specific sensors. It is a JSON array of values, with the following structure:

[
  {
    "serialnumber": "000200610104",
    "slowdown_ms": -10
  },
  {
    "url": "http://192.168.0.13",
    "slowdown_ms": 20
  },
  {
    "productcode": "AL13500",
    "slowdown_ms": 20.01
  }
]

Last modified May 5, 2023: feat: finishing touches (1147002)