Collecting PLC Data with the Beckhoff ADS Driver

In this tutorial, we introduce how to collect data from Beckhoff software PLCs using the EMQX Neuron ADS driver.

Environment Setup

We use two PCs connected to a local area network in this tutorial.

• One is a Linux machine with EMQX Neuron installed. Consult the the installation instruction on how to install EMQX Neuron.
• The other is a Windows machine with TwinCAT 3 installed. Refer to the Beckhoff TwinCAT website to download and install TwinCAT.

	PC 1	PC 2
Operating System	Linux	Windows
IP address	192.168.1.152	192.168.1.107
AMS Net ID	192.168.1.152.1.1	192.168.1.107.1.1
Software	EMQX Neuron	TwinCAT 3
Network	Connected	Connected

Configure TwinCAT

Before EMQX Neuron and the TwinCAT PLC can communicate with each other, we first need to add a static route for EMQX Neuron in TwinCAT. We also need to find the AMS Net ID of the TwinCAT PLC and the index group and index offset of the variables.

Add Static Route in TwinCAT

1. Open the TwinCAT Static Routes dialog box.

_{Fig.1 - Open the TwinCAT static routes dialog}

2. Click **Add**.

_{Fig.2 - TwinCAT static routes dialog}

3. Provide the information as highlighted in the following image. Note that the **AmsNetId** is the IP address of the EMQX Neuron PC appended with ".1.1".

_{Fig.3 - TwinCAT add route dialog}

4. A successfully added route is shown as follows.

_{Fig.4 - TwinCAT static routes dialog updated}

Get AMS Net ID and Port Number

1. Open the TwinCAT System dialog to show the AMS Net ID.

_{Fig.5 - TwinCAT system dialog}

2. By default, TwinCAT PLC port number is 851.

_{Fig.6 - TwinCAT PLC project tab}

Get Index Group and Index Offset of Variables

We use the following TwinCAT PLC program, which defines enough variables for testing in this tutorial.

_{Fig.7 - TwinCAT PLC project main program}

Find the Index Group

The Beckhoff index group/offset page lists the index group to access the PLC memory range. For the %MW field, the index group is 0x4020. For the %MX field, the index group is 0x4021. For the variables b, i8, u8, i16, u16, i32, u32, i64, u64, f32, f64, str defined in the main program, the index group is 0x4040.

_{Fig.8 - TwinCAT index group table}

Find the Index Offset

Open the TwinCAT PLC data area tab to find the index offset of the variables.

_{Fig.9 - TwinCAT PLC data area tab}

Get the Index Group/Offset by TPY File

We could also find the index group and index offset through the TPY file.

1. Ensure TPY File is enabled.

_{Fig.10 - TwinCAT PLC project setting tab}

2. Open the TPY file in the TwinCAT project directory.

_{Fig.11 - TwinCAT PLC project TPY file path}

3. The TPY file contains the index group and index offset of each variable defined in the PLC program.

_{Fig.12 - TwinCAT PLC project TPY file content}

Configure EMQX Neuron

Add ADS South Node

In the EMQX Neuron dashboard, click South Devices -> Add Device to add an ADS node.

_{Fig.13 - Add ADS south device in EMQX Neuron dashboard}

Configure ADS Node

Click the node configuration icon to configure the newly created ADS node.

_{Fig.14 - Configure ADS node in EMQX Neuron dashboard}

Add Tags to the ADS Node

For each variable in the aforementioned TwinCAT PLC program, we add a corresponding tag to the EMQX Neuron ADS node. The [Beckhoff data types] page lists the size of the data types. Together with the program source code we could derive the data types of the tags.

_{Fig.15 - TwinCAT PLC main program}

For tag addresses, the index offset component is shown in the TwinCAT PLC data area tab.

_{Fig.16 - TwinCAT PLC data area tab}

The following figure shows all added tags in the ADS node.

_{Fig.17 - ADS node tags in EMQX Neuron dashboard}

Monitor Data

Read Tags

Once the TwinCAT PLC is in running mode, we could see the variable values in the interface.

_{Fig.18 - TwinCAT variable values in running mode}

In the EMQX Neuron dashboard, click Monitoring -> Data Monitoring, check whether the tag values are read correctly.

_{Fig.19 - EMQX Neuron data monitoring tab}

Write Tags

In the EMQX Neuron Data Monitoring tab, click Write on the main.MXtest1 tag to write a true value.

_{Fig.20 - EMQX Neuron write main.MXtest1}

Click Write on the main.MWtest1 tag to write the value 6666.

_{Fig.21 - EMQX Neuron write main.MWtest1}

After a successful write, we could see that variable values do update in TwinCAT.

_{Fig.22 - TwinCAT variable values updated}