Modbus Multi-Master Connection

Function Introduction

The Modbus multi-master connection function allows multiple master devices to connect to the controller simultaneously, enabling collaborative control of the robot. The controller acts as a slave and supports up to 9 master devices connecting simultaneously, including Modbus Poll software, touch screens, etc.

Environment Requirements

• Hardware Equipment:

  • Controller (supports Modbus function)
  • Computer (with Modbus Poll software installed)
  • Touch screen (supports Modbus protocol)
  • Switch (for connecting controller, computer and touch screen)
  • Ethernet cable

• Software Requirements:

  • Modbus Poll software (for testing multi-master connections)
  • Controller firmware (supports Modbus multi-master function)

Setting Location

On the teach pendant: Settings -> Modbus Settings -> Modbus Parameters

Connection Steps

1. Hardware Connection:

   • Connect the computer and touch screen to the controller through a switch
   • Ensure all devices are on the same network subnet

2. Controller Settings:

   • In the Modbus Parameters interface, select protocol as TCP
   • Set the controller as slave
   • Turn on the connection enable switch
   • Record the controller's IP address and port number

3. Modbus Poll Connection:

   • Open Modbus Poll software
   • Click Connection -> Connect
   • Connection type: select ModbusTCP/IP
   • Enter the controller's IP address and port number
   • Set the scan cycle to be consistent with the teach pendant
   • Click OK to complete the connection

4. Touch Screen Connection:

   • Configure the Modbus TCP connection on the touch screen
   • Enter the controller's IP address and port number
   • Save the configuration and establish the connection

Multi-Master Control

• Maximum 9 masters supported: Multiple Modbus Poll instances and touch screens can connect simultaneously
• Parallel control: Different masters can send commands to the controller simultaneously
• IP address management: Ensure all master device IP addresses do not conflict
• Scan cycle: The scan cycles of all masters should be set reasonably to avoid network congestion

Notes

1. Network Configuration: Ensure all devices are on the same network subnet and IP addresses do not conflict
2. Scan Cycle: Set a reasonable scan cycle to avoid network congestion
3. Connection Quantity: Maximum 9 masters can connect simultaneously. Exceeding this may cause connection failure
4. Priority: When multiple masters send commands simultaneously, the controller processes them in the order received
5. Communication Stability: Ensure the network connection is stable to avoid disconnections

FAQ

Q1: Why can't a multi-master connection be established?

A1: Check the following:

• Ensure the controller's Modbus connection enable switch is turned on
• Verify all devices are on the same network subnet
• Check if IP addresses conflict
• Confirm the port number is set correctly
• Check if the network connection is stable

Q2: What to do when multi-master connection response is slow?

A2: Possible causes and solutions:

• Reduce the number of simultaneously connected masters
• Increase the scan cycle to reduce communication frequency
• Check if network bandwidth is sufficient
• Ensure controller performance meets multi-master requirements

Q3: What to do when data conflicts occur during multi-master connection?

A3: Suggestions:

• Reasonably distribute the control range of different masters
• Avoid multiple masters simultaneously modifying the same parameters
• Consider multi-master collaborative logic in control system design

Q4: How to test if multi-master connection is normal?

A4: The following methods can be used to test:

• Write different address codes in different Modbus Poll instances
• Operate the robot on the touch screen
• Observe whether the controller can correctly respond to all master commands
• Check if the communication status is stable