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The Problems Claude Can’t Solve

The Problems Claude Can’t Solve

AI Is Good at Giving Answers, but It Does Not Bear the Consequences

Recently, I’ve been integrating a PLC into a project. As usual, Claude Code has been my main workhorse, with Cursor and antiGravity assisting in development.

Overall, I’m quite satisfied with these AI tools. However, this time I ran into a problem that none of them could solve independently. In the end, it was resolved through my own analysis.

1. Background: ModBus Communication Between an HMI and a PLC

Communication setup:

  • HMI ↔ PLC

  • Protocol: ModBus TCP

  • Process:

    • Establish a persistent TCP connection
    • Perform application-layer ModBus communication over it

Observed issue:

  • TCP persistent connection ✔️ successful
  • ModBus application-layer communication ❌ failed

2. Debugging Process: Narrowing Down the Root Cause

Solving problems is essentially about pinpointing the issue.

1️⃣ Simulating ModBus Communication with Python

  • Wrote a Python-based ModBus client

  • Included:

    • TCP persistent connection
    • ModBus application-layer requests

Result:

  • TCP connection established successfully
  • Application-layer communication failed

👉 Initial conclusion: not an implementation bug

2️⃣ Packet Capture with Wireshark

  • Captured network traffic for analysis
  • Findings matched the program’s behavior:

Conclusion:

  • TCP handshake completed normally
  • ModBus read requests timed out

📷 (ModBus success vs. failure packet captures can be shown here)

3️⃣ Testing with a Third-Party HMI Tool

  • Used a mature HMI testing application
  • Retested communication with the PLC

Result:

  • TCP connection ✔️
  • Application-layer communication ❌ still failed

📷 (Screenshot placeholder)

4️⃣ Hardware Engineer’s Remote Test (Turning Point)

  • A hardware engineer connected remotely via VPN
  • Used the same HMI testing application

Result:

  • TCP connection ✔️
  • ModBus application-layer communication ✔️ succeeded

📷 (Screenshot placeholder)

3. Root Cause: The Difference Between Success and Failure

At this point, the cause had almost fully surfaced. The question became:

What is the difference between the successful and failed connections?

🔍 Key Difference: IP Subnet

Device IP Address
HMI A 192.168.88.100
HMI B 192.168.0.88
PLC 192.168.88.1

Although all devices were on the same LAN, they were not in the same subnet.

⚠️ Critical Insight

After researching the issue (with GPT assisting the search):

  • The PLC had no gateway configured

  • As a result:

    • TCP layer: connections could be established
    • ModBus application layer: responses could not be routed back correctly

📷 (Network topology or search result screenshot placeholder)

✅ Solution

Configured the development machine with a static IP:

IP: 192.168.88.101

After this change:

  • TCP persistent connection ✔️
  • ModBus communication ✔️ successful

4. Conclusion: A Problem AI Could Not Solve Alone

In this case:

  • AI provided possibilities
  • AI assisted with exploration
  • But it could not identify the final cause or make the decision

AI was an assistant, not the party bearing responsibility.

5. Another Problem AI Cannot Solve: Self-Discipline

There is another problem that neither Claude nor any AI can solve for you: self-discipline.

🏃 Running: Not Willpower, but a Shift in Understanding

I have been running consistently for one and a half years.

This was not driven by the “willpower doctrine” drilled into us during childhood, but by a single statement I once heard in an interview.

🎤 The Interview

The host asked a guest:

Why are you still able to start technology ventures at the age of 50?

The context was clear:

  • Programmers sit for long hours
  • Neck and lower-back problems are common
  • For many, 35 is like a sword of Damocles hanging overhead

The Guest’s Answer

When I feel low on energy or physically uncomfortable, I shut down my computer and phone and go run 5 kilometers.

Every time I finish running, I feel refreshed and energized— like I’ve been fully recharged.

🔁 The Results of Consistency

From that moment on:

  • 2–3 runs per week, each 5 km
  • Running used to require mental preparation
  • Now it’s simply: decide and go

Health improvements:

  • Triglyceride levels normalized
  • Cholesterol reduced
  • Mild fatty liver condition disappeared

6. Sleep: One Sentence That Changed My Routine

Recently, I also started sleeping early and waking early. This change was triggered by a friend.

She is a practitioner of traditional Chinese medicine. She said:

Sleeping early allows the body to truly recover— no medication can replace it.

If sleeping early allows you to still have a working body at 80, while staying up late might end your life at 60 or even earlier, what would you choose?

🕰 My Adjustment

From that day on:

  • 9:30 PM became my preparation time:

    • Wash up
    • Stay away from my phone
    • Get ready for sleep

For someone who has spent years in internet companies, this once felt unimaginable. Now, it has become effortless.

7. Final Thoughts: What AI Cannot Do for You

  • AI can provide answers

  • AI can assist with analysis

  • But AI cannot bear consequences

  • And it certainly cannot:

    • Run for you
    • Go to bed early for you
    • Make life-altering choices on your behalf

Values can overturn everything. When you truly understand the value of something— to the point where it becomes irresistible— action no longer requires willpower.

These are the things no AI agent can do for you.