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Applicable Gateways and Firmware Requirements

1. Manual Description

1.1 Manual Purpose

This manual guides field technicians to quickly configure a Robustel edge computing gateway to collect data from southbound DNP3 devices, including both DNP3 TCP and DNP3 RTU. It also explains how to forward the collected data to northbound systems through MQTT or Modbus TCP.

1.2 Intended Audience

This manual is intended for field implementation engineers and commissioning personnel. You do not need deep theoretical knowledge of the DNP3 protocol. By following the steps in this document, you can complete device connection, tag configuration, data collection, and data forwarding.

1.3 Reading Guide

Because DNP3 supports two different physical connection types, Ethernet for TCP and serial for RTU, it is recommended to follow the reading path below:

• If you are using a DNP3 TCP device: Focus on Chapters 1, 2, and 3 first, then go directly to Chapter 4 for southbound configuration, and finally read Chapters 7, 8, and 9.
• If you are using a DNP3 RTU device: Focus on Chapters 1, 2, and 3 first, then go directly to Chapter 5 for southbound configuration, and finally read Chapters 7, 8, and 9.
• If you do not have a real device and want to learn with a simulator first: After reading Chapters 1, 2, and 3, read Chapter 4 to complete the gateway configuration, and then read Chapter 6 to complete the simulator configuration.

2. Basic Concepts and Network Topology

2.1 Gateway Role in the Network

In a DNP3 network, the Robustel gateway acts as the data collection Master. Its task is to actively initiate requests, read data from underlying DNP3 outstations, such as protection relays, RTUs, and smart meters, and then convert that data into IIoT protocols, such as MQTT or Modbus TCP, for northbound systems.

2.2 Connection Topology

• DNP3 TCP: Devices are connected through standard Ethernet cables. The gateway and the DNP3 device are usually located in the same LAN subnet. If they are not in the same subnet, make sure routing is configured correctly and that the port, usually 20000, is not blocked by a firewall.

Figure 2-1 DNP3 TCP Connection Topology

• DNP3 RTU: Devices are connected in a daisy chain over an RS485 serial bus. Make sure A+ and B- are wired correctly, all devices on the bus use the same baud rate, data bits, parity, and stop bits, and 120-ohm termination resistors are added at both ends of the bus.

Figure 2-2 DNP3 RTU Connection Topology

2.3 DNP3 Collection Architecture: Channel, Device, and Tag

Because DNP3 includes many Master-level common settings, such as master address, event polling cycles, and time synchronization, the system uses a three-layer model of Channel > Device > Tag to avoid repeated configuration when multiple devices are added:

1. Channel: Represents a physical or logical communication link and carries Master-level common parameters, such as TCP IP and port or the RTU serial port. It is not the same as a real field device.
2. Device (Outstation): Belongs under a channel and represents a real field device. It mainly manages the 【Slave Address】 and 【Acquisition Strategy】.
3. Tag: Belongs under a device and represents a specific DNP3 object point, such as Binary Input or Analog Input. It is used for object modeling and data mapping.

3. Preparations

3.1 Hardware and Software Requirements

3.2 Environment and Network Requirements

1. The PC must be in the same subnet as the gateway and be able to communicate with it. The default gateway LAN IP is 192.168.0.1.
2. It is strongly recommended to obtain the device point list from the device vendor in advance. The point list contains key information such as tag meaning, object type, index, and data type.

4. Southbound Configuration: DNP3 TCP

Chapter Goal: Connect and collect data from a DNP3 TCP device. You will complete the following tasks in order: configure the gateway LAN IP, create the channel and device in the same workflow, add tags, and publish the configuration.If your device uses RS485 serial communication, skip this chapter and go directly to Chapter 5.

4.1 Physical Layer: Configure the LAN IP Address

Purpose of this step: Establish basic network communication. Configure the gateway LAN IP so that it can communicate with the target DNP3 TCP device over Ethernet.

1. Log in to the gateway Web interface. The default IP is 192.168.0.1 and the default username and password are admin and admin.
2. Navigate to Network > LAN.
3. Edit LAN1 and set the gateway IP to an address in the same subnet as the DNP3 device. For example, if the device IP is 192.168.0.68, the gateway can be set to 192.168.0.1/24.
4. Click Submit and Save & Apply.

Figure 4-1 Configure the Gateway LAN IP

4.2 Add the DNP3 Outstation and Channel

Purpose of this step: Define the target device and communication link in the data collection engine. Because a channel is mandatory, the system allows you to create a channel while adding a device.

1. Open E2C Factory in the gateway management interface and go to Data Collection > Wired Device.
2. Click Add Device and select DNP3 TCP for 【Driver】 in the pop-up form.
3. The 【Channel】 field will appear. If the drop-down is empty, click Channel Management on the right.
4. In the channel management window, click Add Channel, fill in the parameters below, and click Save:

Notes:

• Set an event polling period to 0 to disable polling for that event class.
• The event polling periods only take effect when Event Polling is enabled on the device and the tag 【Event Class】 is configured as the corresponding Class.

5. Close the channel management window and return to the device form. You can now select DNP3-TCP-CH01 in 【Channel】.
6. Continue filling in the device parameters:

7. Click Save. The device card will appear in the list.

Figure 4-2 Add the DNP3 TCP Device and Channel

4.3 Add Tags

Purpose of this step: Define which DNP3 object points the gateway should read from the device.

1. In the device list, select the DNP3 device you just created.
2. In the tag list area on the right, click Add Tag and configure the parameters according to the device point list:

3. After 【Object type】 is selected, 【Data Type】 and 【Read/Write Permission】 are usually populated automatically. For example, Analog Input usually maps to int and Read Only.
4. Add all required tags one by one and click Save.

For the 【Event Class】 setting, pay attention to the following:

• If you only want to verify whether the basic collection works, it is recommended to set all tags to Class 0 first. This makes the Integrity Polling result the easiest to observe.
• Class 1, Class 2, and Class 3 only become meaningful when the device supports the event mechanism and Event Polling has already been enabled in 【Acquisition Strategy】.
• If a tag is configured as Class 1, 2, or 3, but the corresponding event polling period is not configured at the channel level, or is set to 0, that event class will not be polled as expected.
• If you are not sure which event classes are supported by the field device, confirm the point list or device manual with the vendor before deciding which tags should be configured as Class 1, 2, or 3.

Figure 4-3 Add DNP3 Tags

4.4 Publish the Configuration

The configuration must be published before it takes effect.

1. Click Publish in the upper-right corner of the page.
2. In the confirmation prompt, click Confirm Save. The gateway will begin trying to connect to the DNP3 device.

5. Southbound Configuration: DNP3 RTU

If your field device uses a 2-wire RS485 serial connection, follow this chapter.

5.1 Physical Layer: Configure Serial Parameters

Purpose of this step: Make sure the gateway serial settings match the field device exactly. On an RS485 bus, all devices must use the same communication rate and format.

1. Log in to the gateway Web interface.
2. Navigate to Interface > Serial Port and set 【Serial Port Type】 to RS485.
3. Open E2C Factory and navigate to Edge Computing > System Settings > Serial Port.
4. Find the serial port connected to the device, for example COM1, click edit, and configure 【Baud Rate】, 【Data Bit】, 【Stop Bits】, and 【Parity】 according to the device manual.
5. Click Submit to save.

Figure 5-1 Configure the Gateway Serial Port Parameters

5.2 Add the DNP3 Outstation and Channel

1. Navigate to Data Collection > Wired Device and click Add Device.
2. Select DNP3 RTU for 【Driver】.
3. Click Channel Management next to 【Channel】, and in the pop-up window click Add Channel:

Notes:

• Set an event polling period to 0 to disable polling for that event class.
• The event polling periods only take effect when Event Polling is enabled on the device and the tag 【Event Class】 is configured as the corresponding Class.

4. Save and close the channel management window. In the device form, select this channel and continue filling in the device parameters:

5. Click Save to create the device.

Figure 5-2 Add the DNP3 RTU Device and Channel

5.3 Add Tags

Follow the steps in Section 4.3. Under the device, click Add Tag and select the corresponding 【Object type】 and 【Index】 according to the point list. Save after the configuration is complete.

For RTU scenarios, the same Event Class selection principles from Section 4.3 apply. In addition:

• If multiple devices share one RS485 bus, it is recommended to configure only critical points as Class 1 first, instead of placing a large number of normal points into event polling.
• If the site already shows symptoms such as slow polling or occasional timeout, first increase the Integrity Poll Period and the event polling periods appropriately, and then decide whether Class 2 and Class 3 should remain enabled.

5.4 Publish the Configuration

Click Publish in the upper-right corner to make the configuration take effect. The gateway will start sending collection requests to the RS485 bus.

6. Simulator Configuration (Optional)

If you do not have a real DNP3 device, you can use the CDOAN-DNP3 simulator to verify the gateway collection logic. If you already have a real device, skip directly to Chapter 7.

The simulator example in this chapter uses a DNP3 TCP scenario. If you need to validate DNP3 RTU, the overall approach is basically the same. You only need to replace the network parameter settings here with serial parameter settings and combine them with the RTU channel configuration in Chapter 5.

6.1 Install and Tile the Simulator Views

1. Install and open the CDOAN-DNP3 simulator on the engineering PC. It can be downloaded from www.cdoancal.com.
2. Click Views and make sure Config, DNP3 Parameters, Outstation Configuration, and Communication are all checked.
3. Click Window > Tile so that the four windows are tiled for easier configuration.

Figure 6-1 Simulator Four-Window Tiled Layout

6.2 Configure TCP Outstation Mode

In the Config view, configure the network settings:

• 【Communication Mode】: Select TCP Only.
• 【Outstation IP Address】: Set it to the IP address of the PC running the simulator, for example 192.168.0.68.
• 【Listen Mode】: Select the PC network adapter IP in the same subnet as the gateway, for example 192.168.0.68. It must match the IP address configured in the E2C Factory channel.
• 【Network Port】: Set it to 20000 so that it matches the gateway channel configuration.

6.3 Configure DNP3 Parameters

In the DNP3 Parameters view, configure the link addresses:

• 【of Master】: Set it to 0 so that it matches the gateway channel 【Master Address】.
• 【of Outstation】: Set it to 0 so that it matches the gateway device 【Slave Address】.

6.4 Add Outstation Points and Alternating Data Changes

In the Outstation Configuration view, right-click and choose Add to create points that correspond to the gateway tags. To make data changes easier to observe, you can configure alternating values:

6.5 Start Simulator Communication

Click Communication and choose Outstation to start outstation communication. The simulator will begin waiting for the gateway to connect.

7. Data Collection Verification

Whether you use a real device or a simulator, you must verify that data collection is successful after the configuration is published.

7.1 Verify Device Online Status and Tag Values

1. Navigate to Data Collection > Wired Device.
2. Observe the indicator in the upper-left corner of the device card:

• Green: The device connection is normal. For TCP, this means the connection is established. For RTU, this means serial communication is working normally.
• Red: The device connection has failed. Check the network, wiring, or master and slave address matching.

3. On the same page, check the Status, Latest Value, and Update Time columns in the tag list on the right.
4. If the tag status is normal and the Latest Value shows valid data that refreshes with time, data collection is successful.
5. If a simulator is used, continue observing whether the Analog Input or other tags values change according to the configured frequency to confirm that the gateway keeps receiving updated data.

Figure 7-1 Check DNP3 Device Online Status and Tag Values

8. Northbound Configuration: Two Core Scenarios

After southbound DNP3 data collection is successful, you can package and forward the data to northbound systems.

8.1 Create a Tag Group (Preparation for Data to Cloud)

Purpose of this step: Add the DNP3 tags to be reported into one Tag Group so that the MQTT Publish message can select them as a data source.

1. Navigate to Data to Cloud > Tag Group.
2. Click Create Group, and configure the group name and reporting policy.
3. After the first save, select the DNP3 tag to be reported, for example AI_0_Temperature, in the tag selection window, and then click Save again.

The Tag Group takes effect when saved and does not need to be published separately. In the MQTT Publish message, select this Tag Group as the data source.

Figure 8-1 Create a Tag Group

8.2 Scenario A: Forward to an MQTT Broker (Data to Cloud)

This scenario is used to report collected DNP3 data to an MQTT Broker or cloud platform through Standard MQTT.

1. Navigate to Data to Cloud, click Create Cloud Service, select MQTT as the Cloud Service Type, enter a name, and click Save.
2. In Connection Configuration, complete the following key parameters and save the configuration:

Figure 8-2 Configure the MQTT Cloud Service Connection

3. In Message Management for this Cloud Service, select Publish, click Add, and configure the publishing rule:

Figure 8-3 Configure MQTT Publish Message

4. After saving, confirm that the Cloud Service status is normal, and use an MQTT client to subscribe to the corresponding topic.
5. Wait for at least one complete reporting interval and confirm that a message containing AI_0_Temperature and its value is received.

Figure 8-4 Validate MQTT Data to Cloud

8.3 Scenario B: Forward Data Through Modbus TCP

This scenario is used to provide collected DNP3 data to a local SCADA system, HMI, or any other Modbus TCP client. In this scenario, the gateway acts as a Modbus TCP Slave and exposes the mapped tag values for external reading.

1. Navigate to Data Forwarding, click New, select Modbus TCP Slave for 【Protocol】, and click Save.
2. Open the Configuration tab, enable the service, complete the following core parameters, and click Submit.

Figure 8-5 Configure the Modbus TCP Slave Service

3. In the slave list, click Add to create a mapping table, and complete the following parameters:

4. Open the mapping table, click Add, select the collected DNP3 device and AI tag, and configure the mapping parameters as follows:

5. In the SCADA software or a Modbus TCP client, enter the gateway IP address, port 502, and slave address 1. Use function code 04 to read mapping address 1, and verify that the returned value matches AI_0_Temperature on the Data Collection page.

If the client uses a zero-based offset address, mapping address 1 may need to be entered as 0. If the client cannot read data, first check whether the Modbus TCP Slave service is enabled, whether the port and slave address are correct, and whether AI_0_Temperature already has a latest value on the Data Collection page.

Figure 8-6 Validate Modbus TCP Data Forwarding

9. Troubleshooting and FAQ

9.1 Common DNP3 TCP Issues

9.2 Common DNP3 RTU Issues