How Siemens PLC Works Perfectly with Collaborative Robots

How Siemens PLC Works Perfectly with Collaborative Robots? Unveiling the Core Control Technology of Human-Machine Collaboration, Leading a New Model of Intelligent Manufacturing!

Hello everyone, I am Hanhan. Today we are going to talk about a hot topic: how Siemens PLC works together with collaborative robots. This is not a high-end concept, but a real productivity enhancement tool. Come, let’s explore how this “golden duo” plays in intelligent manufacturing!

1.

The “Double Sword Combination” of PLC and Collaborative Robots

When it comes to factory automation, PLC is definitely the big brother. And collaborative robots are like the new young guys, flexible and obedient. Combining these two results in an effect of 1+1>2.

PLC acts as the brain of the factory, responsible for overall coordination. The collaborative robot is the flexible arm that can precisely perform various complex actions. The two communicate through protocols, achieving seamless cooperation.

2.

Hardware Connection: The First Step to Successful Partnership

To let the PLC and the collaborative robot have a good relationship, the first step is to get them “connected”. Generally, we use the PROFINET industrial Ethernet protocol. In simple terms, it means connecting the PLC and the robot controller with an Ethernet cable.

[PLC] <-- Ethernet cable --> [Switch] <-- Ethernet cable --> [Robot Controller]

Notes: Don’t underestimate this Ethernet cable! Using industrial-grade cables is a must; ordinary cables might suffer from electromagnetic interference.

3.

PLC Program: The Art of Commanding

The PLC, as the “conductor,” needs to write a good “score” (program) to command the collaborative robot, the “musician.” Let’s take a look at this simple ladder diagram program:

|--[ ]--|   Robot Ready   |--( )--|   Start Robot   |
|               |
|--[/]--|   Emergency Stop    |
|--[ ]--|   Robot Ready   |--[/]--|   Robot Running |--( )--|   Send Position Data |
|               |                       |
|--[ ]--|   Start Robot   |                       |
|--[ ]--|   Robot Completed   |--( )--|   Next Action   |

This program achieves:

1. Check if the robot is ready and if the emergency stop is pressed

2. Start the robot when conditions are met

3. Send position data while the robot is running

4. Proceed to the next step after the robot completes its action

Key Point: The data exchange between the PLC and the robot is crucial! The robot’s status, position, and other information must be communicated to the PLC in a timely manner for it to make correct decisions.

4.

Collaborative Robot Program: A Flexible Dance

The collaborative robot also cannot be idle. It needs to receive commands from the PLC and perform corresponding actions. Taking the Universal Robots UR robot as an example, we can program it using its scripting language:

def main():
    while True:
        if get_standard_digital_in(0):  # Check PLC's start signal
            move_to_target()  # Move to target position
            send_position()   # Send current position to PLC
            set_standard_digital_out(1, True)  # Notify PLC that action is complete
            sync()

def move_to_target():
    target = p[0.4, 0.1, 0.5, 0, 3.14, 0]  # Target position
    movel(target, a=1.2, v=0.25, r=0)

def send_position():
    current_pos = get_actual_tcp_pose()
    socket_send_string(str(current_pos))

main()

This program achieves:

1. Continuously checks for the PLC’s start signal

2. Moves to the designated position upon receiving the signal

3. Sends the current position to the PLC

4. Notifies the PLC that the action is complete

Tip: Programming collaborative robots is much simpler than traditional industrial robots; often, you can directly teach them without writing complex code.

5.

Real Application Case: The “Best Partner” on the Assembly Line

Imagine this scenario on an automotive parts assembly line:

1. The PLC controls the conveyor belt, transporting the parts to be assembled to the workstation

2. The PLC instructs the collaborative robot to start working

3. The robot picks up parts from the bin and performs precise assembly

4. After assembly, the robot reports to the PLC

5. The PLC controls the conveyor belt to move the completed product away while preparing the next workpiece

In this process, the PLC is responsible for overall scheduling, while the collaborative robot handles detailed operations. The advantages of human-machine collaboration are that the robot can work continuously and efficiently, while operators can focus on quality inspection and handling exceptions.

6.

Common Problems and Solutions

1. Communication Interruption:

* Problem: The PLC suddenly cannot receive data from the robot
* Solution: Check the Ethernet cable connection, view the switch status, and confirm if the IP address setting is correct

1. Robot Movement Inaccuracy:

* Problem: The robot always seems to miss grabbing the part accurately
* Solution: Recalibrate the robot, or add position compensation logic in the PLC program

1. Program Logic Error:

* Problem: The robot and PLC coordination "jumps"
* Solution: Carefully review the program flow to ensure each step has clear start and end signals

Hard-earned lesson: Once, during debugging, I forgot to set a force limit for the robot. As a result, it was too “enthusiastic” and crushed a fragile part. The lesson is: Safety First! Always set appropriate force and speed limits.

7.

Practical Recommendations

1. Start with simple tasks and gradually increase complexity

2. Use simulation software for testing to avoid damage to physical objects

3. Establish a detailed error logging system for easier troubleshooting

4. Regularly perform system backups as a precaution

5. Pay attention to safety settings, including the robot’s force limits and the PLC’s emergency stop function

Remember, Rome wasn’t built in a day. Mastering the combination of PLC and collaborative robots takes time and practice. Get hands-on, think critically, and you will soon become an “automation expert” in the factory!