Protocol Overview

• Protocol Description: BACnet MS/TP (Master-Slave/Token-Passing) is a physical layer and data link layer implementation of the BACnet protocol, designed for low-speed, low-cost application scenarios. It adopts a master-slave/token-passing mechanism and connects devices via an RS-485 serial bus to enable data communication and control between devices. It is commonly used for controllers, sensors, actuators and other devices in building automation.
• Application Scenarios: This protocol is widely used in building automation systems such as HVAC (Heating, Ventilation, and Air Conditioning), access control, and lighting control, especially suitable for scenarios with long wiring distances, scattered nodes but low data rate requirements.
• Edge2Cloud Factory Support: As a client, Edge2Cloud Factory supports connecting to and collecting device data on the serial bus through the BACnet MS/TP protocol, and supports automatic search and manual configuration of devices.

Prerequisites

Before starting the configuration, ensure the following preparations are completed:

• Hardware Connection:a. Use an RS-485 serial cable to connect the designated serial port (e.g., COM2) of the Edge2Cloud Factory device to the target BACnet MS/TP bus.b. Ensure the bus wiring is correct (A/B lines) and the terminal resistor is configured properly (if needed).c. Connect the debugging computer to the Edge2Cloud Factory gateway for configuration.
• Network Parameters:a. Not applicable. The MS/TP protocol uses serial ports instead of IP networks.b. Ensure the serial port parameters (baud rate, data bits, parity bits, stop bits) of the Edge2Cloud Factory are consistent with those of other devices on the bus.
• Device Parameters:a. Prepare the Device ID (Device Instance Number) of the target BACnet device.b. Determine the Physical Address (MAC Address) of the target device on the bus (this address can be automatically discovered in some automatic search scenarios but is required for manual addition).c. Determine parameters such as Polling Cycle, Maximum Number of Information Frames, Maximum Number of Master Devices, etc.

Configuration Steps

Please follow the steps below to configure in the Web interface of Edge2Cloud Factory.

Add Device

Step 1: Open the Entry

Log in to the Edge2Cloud Factory management interface. Log in to the gateway management page -> [Data Collection] to enter the Edge2Cloud Factory configuration page.

Two methods are supported: Add Manually (Single Device) or Auto Search (Batch Devices).

Method 1: Manually Add a Single Device

Step 1: Add DeviceClick the "Create Device" button, fill in the device name (ensure uniqueness), and select the BACnet MS/TP protocol.

Step 2: Supplement InformationFill in the information on the current page, note do not click the [Auto Search] button, then save and submit after completion.Click the "Publish" button in the upper right corner of the page to make the configuration take effect.

Method 2: Automatically Search for Multiple Devices

Step 1: Add DeviceClick the "Create Device" button and directly select the BACnet MS/TP protocol.

Step 2: Auto SearchClick the "Auto Search" button to jump to the auto search device pop-up, supplement the information, and click [Search].

Step 3: Select DevicesYou can check multiple devices in the list and click "Next" to perform batch addition.

The default device name is the original device name found by the search. Note that device names in the system cannot be duplicated; if duplicated, you can click to modify them directly.

Step 4: Other ConfigurationsAfter supplementing and confirming the following information, click "Save" to complete the batch addition of devices, or click "Save and Configure Variables" to continue quick batch configuration of device variables.

Click the "Publish" button in the upper right corner of the page to make the configuration take effect.

Step 5: Configure VariablesIf you clicked "Save and Configure Variables" in the previous step, you can quickly configure device variables in batches.

• The left side is the search result area, and the right side is the batch addition area.
• The top of the left side supports searching for object names/types and switching devices to search for corresponding variables.
• Select multiple variables on the left, click the [Subscribe] or [Poll] button in the middle to add them to the right.
• The default variable name is the object name; variable names within a single device in the system cannot be duplicated and cannot contain spaces, so the system will automatically remove spaces.
• After clicking Save, you can view the successfully added devices and point table information.

Add Tag

Two methods: Add Manually (Single Tag) or Auto Search (Batch Tags).

Method 1: Manually Add a Single Variable

1. Step 1: Add VariableClick the "Manual Addition" button, fill in the information, and save.

Repeat this step to add all variables that need to be collected. After all variables are added/modified, click the "Publish" button in the upper right corner of the page to make the configuration take effect.

Method 2: Batch Auto Search and Add Variables

1. Step 1: Auto SearchClick the "Auto Search" button, select the required variables, click [Subscribe] or [Poll] to select them to the right, and click [Save] to add them in batches.

After all variables are added/modified, click the "Publish" button in the upper right corner of the page to make the configuration take effect.

Verification & Troubleshooting

• Devices cannot be found or connected successfully:
  • Check whether the Edge2Cloud Factory and the target device are correctly connected to the same RS-485 bus, and whether the A/B lines are reversed.
  • Check whether the serial port parameters (baud rate, data bits, parity bits, stop bits) are consistent with all devices on the bus.
  • Check whether the "Local Node Address" conflicts with the addresses of other devices on the bus.
  • Check whether the "Maximum Number of Master Devices" is set correctly (should be greater than or equal to the highest address of the master devices on the bus).
  • Confirm whether the terminal resistor configuration on the bus is correct (usually at both ends of the bus).
• Data collection fails or communication is unstable:
  • Verify whether the configuration of the device's Device ID, Object Type, and Instance Number is correct.
  • Check whether parameters such as "Polling Cycle", "Collection Timeout", and "Communication Interval Time" are set reasonably (whether they are too short leading to untimely device responses).
  • Check whether the bus load is too heavy; try adjusting the "Maximum Number of Information Frames".
  • Check whether there is interference in the line; ensure the RS-485 line is far away from high-voltage lines.
• Question: Where to view relevant logs when an exception occurs?
  • Debug Logs:

Appendix

Protocol Data Type Corresponding Description

When configuring variables in Edge2Cloud Factory, the data type correspondence is as follows:

Detailed Explanation of MS/TP Key Parameters

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