| // |
| // Licensed to the Apache Software Foundation (ASF) under one or more |
| // contributor license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright ownership. |
| // The ASF licenses this file to You under the Apache License, Version 2.0 |
| // (the "License"); you may not use this file except in compliance with |
| // the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| :imagesdir: images/ |
| |
| == About PLC4J |
| |
| `PLC4J` is a sub-project of `PLC4X` with implementations based on `Java` targeted at runtimes for `Java 1.8` or above. |
| |
| One of PLC4X's core principals is, that an application using PLC4X should be independent of the PLC or protocol being used. |
| |
| When addressing a resource on a remote there are two parts that are dependent on the protocol and the type of PLC: |
| |
| - Addressing the PLC itself |
| - Addressing a resource on the PLC |
| |
| Providing this independence to addressing the PLC itself is completely handled by the `PlcDriverManager` the application requests a connection from. |
| |
| Hereby the design of the `url string` passed to the `getConnection` method is greatly inspired by `JDBC`. |
| |
| The protocol prefix of the url specifies the type of driver being used. |
| |
| For example, when connecting to a Siemens PLC using the S7/Step7 Protocol, the url: `s7://192.42.0.98/1/2` causes the driver manager to create a S7 connection instance. |
| The part behind the `:` is hereby used by the driver implementation to configure that particular connection. |
| |
| For a S7 connection, for example, this is `IP address/host name`/`rack number`/`slot number`. For different types of connections this url structure will greatly differ. |
| |
| As mentioned above, the second platform dependent information is the address of resources on a PLC. |
| The format of an address greatly depends on the type of connection. Therefore `parseAddress` is one of the only methods defined in the `PlcConnection` interface any connection has to implement. |
| |
| This method returns an object implementing the `Address` interface which then can be used by the same connection to identify remote resources. |
| |
| [ditaa,plc4x-architecture] |
| .... |
| +----------------------------------------------------------------------------------------------+ |
| |c05A | |
| | | |
| | User Application | |
| | | |
| | | |
| | +-----------+------------------+------------------+------------------+------+ |
| | | | | | | |
| | | | | | | |
| | | v v v v |
| | | +-------------+ +-------------+ +-------------+ +-------------+ |
| | | |c0BA | |c0BA | |c0BA | |c0BA | |
| | | | Apache | | Apache | | Apache | | Apache | |
| | | | Kafka | | Camel | | Edgent | | Nifi | |
| | | | Connect | | Integration | | Integration | | Integration | |
| | | | | | | | | | | |
| +---------+--------+ +------+------+ +------+------+ +------+------+ +------+------+ |
| | | | | | |
| | | | | | |
| v v v v v |
| +----------------------------------------------------------------------------------------------+ |
| |cAAA | |
| | | |
| | PLC4X API | |
| | | |
| | | |
| +------+---------------+---------------+---------------+---------------+---------------+-------+ |
| | | | | | | |
| | | | | | | |
| v v v v v v |
| +-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+ |
| |c0BA | |c0BA | |c0BA | |c0BA | |c0BA | |c05A | |
| | Siemens | | Beckhoff | | Modbus | | OPC UA | | Emerson | | User | |
| | S7 | | ADS | | Driver | | Driver | | DeltaV | | Driver | |
| | Driver | | Driver | | | | | | Driver | | | |
| | | | | | | | | | | | | |
| +-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+ |
| .... |
| |
| === Usage |
| |
| Below code example connects to a remote Siemens S7 PLC using the S7/Step7 protocol and then reads the state of the `inputs` and `outputs` from this. |
| |
| It also demonstrates two ways this information can be accessed: |
| |
| - Synchronously (The application pauses, till the response is received) |
| - Asynchronously (The application continues and can |
| |
| [source,java] |
| ---- |
| include::../../../../examples/hello-world-plc4x/src/main/java/org/apache/plc4x/java/examples/helloplc4x/HelloPlc4x.java[lines=19..200] |
| ---- |
| |
