PLC4X

Since Camel 3.20

Both producer and consumer are supported

The Camel Component for PLC4X allows you to create routes using the PLC4X API to read from a Programmable Logic Controllers (PLC) device or write to it.

URI Format

plc4x://driver[?options]

The bucket will be created if it doesn’t already exist.

You can append query options to the URI in the following format: ?options=value&option2=value&…​.

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

At the component level, you set general and shared configurations that are, then, inherited by the endpoints. It is the highest configuration level.

For example, a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre-configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

You can configure components using:

  • the Component DSL.

  • in a configuration file (application.properties, *.yaml files, etc).

  • directly in the Java code.

Configuring Endpoint Options

You usually spend more time setting up endpoints because they have many options. These options help you customize what you want the endpoint to do. The options are also categorized into whether the endpoint is used as a consumer (from), as a producer (to), or both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.

A good practice when configuring options is to use Property Placeholders.

Property placeholders provide a few benefits:

  • They help prevent using hardcoded urls, port numbers, sensitive information, and other settings.

  • They allow externalizing the configuration from the code.

  • They help the code to become more flexible and reusable.

The following two sections list all the options, firstly for the component followed by the endpoint.

Component Options

The PLC4X component supports 3 options, which are listed below.

Name Description Default Type

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

Endpoint Options

The PLC4X endpoint is configured using URI syntax:

plc4x:driver

With the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

driver (common)

Required PLC4X connection string for the connection to the target.

String

Query Parameters (8 parameters)

Name Description Default Type

autoReconnect (common)

Whether to reconnect when no connection is present upon doing a request.

false

boolean

period (consumer)

Interval on which the Trigger should be checked.

int

tags (consumer)

Tags as key/values from the Map to use in query.

Map

trigger (consumer)

Query to a trigger. On a rising edge of the trigger, the tags will be read once.

String

bridgeErrorHandler (consumer (advanced))

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

exceptionHandler (consumer (advanced))

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer (advanced))

Sets the exchange pattern when the consumer creates an exchange.

Enum values:

  • InOnly

  • InOut

ExchangePattern

lazyStartProducer (producer (advanced))

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

Dependencies

Maven users will need to add the following dependency to their pom.xml.

pom.xml

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-plc4x</artifactId>
    <version>${camel-version}</version>
</dependency>

where ${camel-version} must be replaced by the actual version of Camel.

Usage

The Camel PLC4X component supports various protocols by adding the driver dependencies:

  • Allen Bradley ETH

  • Automation Device Specification (ADS)

  • CANopen

  • EtherNet/IP

  • Firmata

  • KNXnet/IP

  • Modbus (TCP/UDP/Serial)

  • Open Platform Communications Unified Architecture (OPC UA)

  • Step7 (S7)

The list of supported protocols is growing in PLC4X. There are good chances that they will work out of the box just by adding the driver dependency. You can check here.

Consumer

The consumer supports one-time reading or Triggered Reading. To read from the PLC, use a Map<String,String> containing the Alias and Queries for the Data you want (tags).

You can configure the tags using tag.key=value in the URI, and you can repeat this for multiple tags.

The Body created by the Consumer will be a Map<String,Object> containing the Aliases and their associated value read from the PLC.

Polling Consumer

The polling consumer supports consecutive reading. The input and output are the same as for the regular consumer.

Producer

To write data to the PLC, we also use a Map. The difference with the Producer is that the Value of the Map has also to be a Map. Also, this Map has to be set into the Body of the Message

The used Map would be a Map<String,Map<String,Object> where the Map<String,Object> represent the Query and the data we want to write to it.

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