1. Protocol Overview

• Protocol Description: Modbus RTU is a standard industrial automation protocol that transmits binary data over serial links (e.g., RS-232 or RS-485).
• Application Scenarios: Widely used for devices that support serial communication, such as VFDs, smart meters, temperature controllers, and various PLCs.
• E2C Trinity Support: E2C Trinity acts as a Master to connect and read data from slave devices via the gateway's serial port.

2. Prerequisites

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

• Hardware Connection:
  • Ensure the E2C Trinity gateway's serial port (RS-485 or RS-232) is connected to the target device via shielded twisted pair cable.
  • Verify correct wiring (e.g., for RS-485, ensure A+ and B- are not reversed).
• Serial Parameter Verification:
  • Confirm the target device's serial parameters: Baud Rate, Data Bit, Parity (Check Bit), and Stop Bit.
  • All devices on the same serial link must share the same serial parameters.
• Tag List Preparation:
  • Obtain the Modbus register address table for the device.
  • Identify key parameters: Slave ID, Function Code, Register Address, and Data Type.

3. Configuration Steps

Follow these steps within the E2C Trinity Web interface.

Step 1: Create Device

1. Log into the gateway management page. Navigate to [Data Acquisition] to enter the E2C Trinity configuration page.

1. Click the "Create Device"button and fill in the connection information in the pop-up window.

1. Click "Save" to complete the device creation.

Step 2: Configure Tag (Point Table)

1. Select the newly created device from the device list on the left.
2. Click "Add" to create a single data acquisition Tag. Fill in the tag information.

1. Repeat for all tags. Once finished, click "Publish" in the top right corner to apply the configuration.

4. Verification & Troubleshooting

Verification

1. Check the device list to ensure the status is Online and tags are successfully collected.A green icon indicates success, and a red icon indicates failure.

1. View the Latest Value column to verify data accuracy.

1. Test Writing: Click the edit icon in the "Latest Value" column, modify the value, and verify if the PLC accepts the change.

Common Troubleshooting

• Problem: Device fails to connect for a long time?
  • Check Physical Link: Ensure the gateway’s serial port (RS-485/RS-232) is securely wired to the device, and A+ / B- are not reversed.
  • Verify Serial Parameters: Confirm that the Baud Rate, Data Bit, Parity, and Stop Bit configured in the gateway match the slave device exactly.
  • Slave ID Confirmation: Ensure the "Slave ID" in the settings matches the device's actual hardware DIP switch or software ID.
  • Link Conflict: Check if multiple slave devices on the same RS-485 bus have conflicting Slave IDs.
• Problem: Device is Online, but tag values are null or incorrect?
  • Verify Tag Parameters: Re-check the Function Code, Register Address, and Data Type against the device’s point table.
  • Byte Order Issues: If numeric values (like Float) are extremely large or garbled, try switching the "Byte Order" (e.g., from ABCD to CDAB or BADC) in the device settings.
  • Address Offset: Some devices have a ±1 address offset (e.g., PLC address 40001 might correspond to protocol address 0 or 1). Try adjusting the address slightly.
• Problem: Data write failed?
  • Access Rights: Ensure the tag's "Access Right" is set to "Read/Write" or "Restricted by FC".
  • FC Support: Confirm the selected Function Code supports write operations (e.g., some Holding Registers are read-only on specific devices).
  • Write Protection: Check if the target device has a physical hardware lock or software-level write protection enabled.
• Where to find logs?
  • Check the Debug Logs or System Logs in the management interface for specific error codes.

5. Appendix

Data Type Mapping

When configuring tags in E2C Trinity, use the following mapping: