Chapter 171: Threshold and the Wager

At six on Thursday morning, the sky was still not fully light. Lin Chen took an ice pack from the freezer compartment, wrapped it in two thin towels, and pressed it to his left ankle. Most of the swelling had gone down, but there was still a hard knot under the skin, and a dull pain rose when his fingertips pressed on it. He swallowed two ibuprofen tablets with warm water. The pills slid down his throat and left behind a faint bitterness. He changed into loose trousers and an old pair of sneakers, tying the laces very loosely to leave room for cushioning.

Spread across the table were three printed copies of the application, the USB drive containing the V3.0 source code, and the draft risk-sharing agreement from the Provincial Department of Industry and Information Technology. The edges of the paper still carried a trace of warmth from the printer. He checked them page by page and drew two red lines beneath Quarterly downtime reduction ≥ 12%. A threshold was not a slogan. It was a math problem. He opened his notebook and wrote out the derivation: the average unplanned downtime of the stamping presses on the Phase II line was currently 4.2 hours per month, or 12.6 hours per quarter. A 12 percent reduction meant quarterly downtime had to be kept within 11.1 hours. The margin for error was only 1.5 hours. Any chain shutdown triggered by a false sensor alarm would punch straight through the bottom line. He had to add a manual review buffer to the script, stretching the delay from warning to execution to three minutes and leaving the factory a window to intervene.

At seven forty, he locked the door and went downstairs. The early bus was packed with students hurrying to class and office workers heading in. He gripped the handrail and tried to keep most of his weight on his right leg. The bus jolted constantly, and each sway sent a fine, needling pain through his left ankle. He closed his eyes and ran through the logic of his report in his head: first the V3.0 architecture and stress-test data, then the field logs, and finally the risk-mitigation plan for the wager agreement. No detours. No exaggeration. What Professor Zhou wanted was something that could actually be implemented, not a concept floating on a PowerPoint slide.

At eight fifty, he arrived at the School of Computer Science building at Provincial Institute of Technology. The corridor smelled of rosin and old paper. At the end of the third floor was the office for industry-academia collaboration. The door was ajar. Lin Chen knocked and heard a curt “Come in.”

Professor Zhou sat behind his desk wearing reading glasses, looking through a journal. Beside him stood a doctoral student in black-rimmed glasses holding a tablet. Two half-finished cups of tea sat on the desk, a few tea leaves floating on the surface.

“Sit,” Professor Zhou said, glancing up. His eyes swept over Lin Chen’s foot, but he asked no questions, only pointed toward the computer. “Did you bring everything?”

“I did.” Lin Chen inserted the USB drive and switched on the projector. The screen lit up, and the class structure diagram for V3.0 spread open. He did not bother with animation. He went straight to the core modules: the data-cleaning layer, the logging layer, and the exception-handling layer.

“How did you set the weights for the sliding-window filter?” the doctoral student asked.

“Based on the sensor baseline from the past three months. The weights decay over time, and new data accounts for no more than thirty percent, to prevent sudden spikes from distorting the overall trend.” Lin Chen pulled up the stress-test curve. “The memory leak has already been fixed. After four continuous hours of operation, usage stays stable at forty-two percent. The logging module writes asynchronously, so it doesn’t block the main thread.”

Professor Zhou pushed up his glasses and leaned forward. “I’ve read the bureau’s wager agreement. Twelve percentage points. They’ve set the line very tight. The factory’s equipment is badly aged, and the voltage fluctuates a lot. If your script misjudges once and causes the line to emergency-stop, who takes responsibility?”

“The script is only responsible for data cleaning and early warning. It does not directly control the PLC.” Lin Chen’s voice stayed even. “The warning threshold is set at two levels. Level one is a yellow light, which prompts manual review. Level two is a red light, which triggers a shutdown recommendation. Every operation leaves a trace, and the logs are uploaded to the cloud in real time. If a shutdown occurs because the factory fails to respond in time, the algorithm is not at fault. I’ve already added an exemption clause to the agreement and attached the operating SOP.”

Professor Zhou was silent for a few seconds, his fingers tapping twice on the desk. “The logic holds. But the lab doesn’t stamp things out of charity. Intellectual-property ownership follows university rules. The lab takes seventy percent, you take thirty. Deployment, maintenance, and on-site debugging will all be your responsibility. The lab provides the test environment and academic endorsement. If the pilot fails, you bear the hardware costs. If the lab’s reputation is damaged, further cooperation ends. Can you accept that?”

“Yes.” Lin Chen did not hesitate. He had already done the math on this. Thirty percent of the IP in exchange for provincial pilot qualification and a university channel was leverage. The hardware cost eight hundred per set. He still had enough left to absorb it. The risk was controllable. The return was clear.

Professor Zhou nodded, took a draft agreement already stamped across the page joins from his drawer, and pushed it over. “Sign it. I’ll submit the materials to the Equipment Office on Thursday afternoon. Take the interface protocol for the Yangtze River Delta project with you while you’re at it.”

Lin Chen accepted the pen and wrote his name in the signature block for Party B. The nib scratched softly across the page. When he finished writing his name, he let out a long breath—not from relief, but from confirmation. The road had been laid beneath his feet. The next step was to tread it solidly.

The doctoral student handed him a folder. Lin Chen opened it. Inside was the communication protocol documentation for the Yangtze River Delta Industrial Internet of Things project: Modbus TCP, the register address mapping table, the data-frame format. He scanned it quickly, and his brow tightened.

“The provincial pilot uses OPC UA over serial conversion, but the Yangtze River Delta project goes directly over Ethernet. The protocol stack is different.” He looked up. “We’ll need an adaptation middleware layer to parse Modbus frames and map them into V3.0’s internal data structure. The workload isn’t heavy, but it will need packet capture and on-site verification.”

“I’m giving you two weeks,” Professor Zhou said. “The pilot application and the interface adaptation proceed in parallel. Don’t drag it out.”

“Understood.” Lin Chen put away the documents and rose to leave. When his left foot touched the floor, a sharp stab came from the hard knot in his ankle. His face did not change. He thanked them and stepped out of the office.

The corridor was brighter now than it had been in the morning. He leaned against the wall and slowly adjusted his breathing. The ibuprofen had begun to take effect, dulling the pain. He took out his phone and checked his bank balance. The pilot advance payment had not come in yet. There was still 412.6 yuan left on his card. He opened the transfer screen, entered his mother’s account number, and sent 300. Memo: For medicine. Sent. The balance dropped to 112.6 yuan. Enough for two weeks of cafeteria meals. Enough for ice packs and pain-relief patches. The rest would have to wait for the advance. He put away his phone, picked up the shockproof case, and slowly walked down the stairs.

At two in the afternoon, he was back in his rented room. Spread across the desk were the Yangtze River Delta project’s protocol documents and an old router. He needed to build a simulated environment and capture packets to test the Modbus frame parser. He plugged in the network cable, powered on the router, and watched the indicator lights begin to blink. Then he opened a terminal, entered his commands, and began writing the code for the adaptation layer.

class ModbusAdapter: def __init__(self, ip, port): self.conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM) ...

He typed line after line, the logic clean and clear. But when he ran the test script and simulated the factory PLC sending data, the terminal suddenly threw an error: ConnectionRefusedError: [WinError 10061] No connection could be made because the target machine actively refused it.

He checked the IP and port. They were correct. The firewall was already off. He switched to another packet-capture tool and monitored the local loopback address. The packets had definitely gone out, but the PLC simulator was not responding. He stared at the screen, fingers suspended over the keyboard. It was not a code problem. It was a protocol-version problem. The factory was using Modbus RTU over TCP, with two extra bytes of CRC check code in the frame header. V3.0’s parser handled the traffic as standard Modbus TCP by default and discarded any packet carrying the check bytes.

He flipped open the appendix to the protocol document. Sure enough, there was a line in small print: Some older PLC firmware retains the RTU frame structure and requires compatibility handling.

Lin Chen leaned back in his chair and rubbed the space between his brows. Compatibility handling meant rewriting the parser logic and adding state-machine judgment. Time had become tight again. He picked up his pen and wrote in his notebook: 1. Add RTU/TCP dual-mode recognition; 2. Logic for stripping verification bytes; 3. Stress-test validation.

Outside the window came the drawn-out, level call of a junk collector. He poured himself a cup of cold water and drank it slowly. His left foot had started aching faintly again, and he got up to replace the ice pack. There was no irritation in him, only calculation. Break the problem apart. Execute the steps. Since walking from Qingshi Village into the provincial capital, that was the only rule of survival he had ever proven true.

His phone vibrated. A text from Old Chen: Friday, 9:00 a.m., on-site verification for the Phase II line. Bring the V3.0 terminal and deployment tools. The factory’s equipment section will cooperate.

Lin Chen stared at the screen, thumb hovering over the keypad. Friday. Tomorrow. The adaptation layer still was not finished, and the field environment was still unknown. He replied: Received. I’ll be there on time.

Sent. He closed the computer, got up, and switched off the light. In the darkness, he slowly lay down, his left foot resting on a folded towel. Outside the window, the wind passed through the anti-theft bars with a faint hum. He closed his eyes, breathing evenly. The next step was Friday’s on-site visit. And the verification bytes in the adaptation layer were already etched into his mind.