1. Basic Understanding of Equipment

1.1 Key Technical Specifications

LISUN Model	GDJW-100*	GDJW-225*	GDJW-500*	GDJW-010*	GDJW-015*	GDJW-020*
Working Compartment Dimensions (cm)	41 × 55 × 45	50 × 60 × 75	70 × 80 × 90	100 × 100 × 100	100 × 100 × 150	100 × 100 × 200
Temperature Range	A: -20°C to 150°C B: -40°C to 150°C C: -60°C to 150°C D: -70°C to 150°C
Variability/Uniformity	±0.5°C/±2°C
Rate of temperature rise	1.0°C to 3.0°C per minute
Cooling Rate	0.7°C to 1.0°C per minute

1.2 Unboxing and Checking the Contents

1.2.1 Unpacking and Visual Inspection

When unpacking the equipment, handle it gently to avoid scratching the exterior casing with sharp tools. After unpacking, first inspect the exterior of the main unit to ensure there is no visible deformation, dents, or peeling paint, and that the panel instruments and buttons are not damaged or loose. If you discover any damage or deformation to the equipment or accessories, do not power it on. Contact LISUN customer service immediately.

1.2.2 Host-type

1 High and Low Temperature Chamber.

1.2.3 Consumables and Accessories

Open the accessory box. Standard accessories include: a spare solid-state relay, rubber plugs, and spare fuses.

Figure 2

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1.3 Description of Equipment Structure

1.3.1 Front View of the Test Chamber

① Control panel; ② Test chamber door (single or double, depending on the size of the test chamber); ③ Condenser ventilation openings.

Figure 3

1.3.2 Rear and Side Views of the Test Chamber

① Power cord; ② Refrigerant pressure gauge; ③ This is the overflow outlet; a small amount of water will flow out during the test. Simply connect this water pipe to a drain. A water pipe with an inner diameter of 10 mm is required.

Figure 4

2. Safety Precautions

2.1 Electrical Safety

2.1.1 Power Connection

The equipment must be powered by a dedicated circuit with specifications of AC 380 V, 50 Hz (or 60 Hz, optional), three-phase, five-wire system. Multiple units must not share a single power source to prevent voltage drops that could cause abnormal equipment performance or unplanned downtime. Before connecting the power supply, ensure the power is turned off. When wiring, strictly distinguish between the live wires (L1, L2, L3), neutral wire (N), and ground wire (PE). The wiring sequence must comply with the requirements of the equipment’s electrical schematic; reversing the live and neutral wires is strictly prohibited.

The equipment is equipped with a phase sequence protector. After wiring, check the phase sequence before powering on: If the green “Un” light and the yellow “R” light on the phase sequence protector are both lit, the wiring is correct; If only one of the lights is on, or none are on, this indicates reverse phase. Turn off the main power supply, swap the positions of the two adjacent live wires (L1 and L2), and then check again;

Figure 5

After completing the wiring, pull firmly on the terminal to ensure the connection is secure and there is no looseness.

2.1.2 Grounding Specifications

The equipment must be reliably grounded, with a grounding resistance of ≤50 Ω. Do not use gas lines, non-metallic water pipes, or neutral wires as substitutes for the grounding wire. After grounding is complete, use a Grounding Resistance Tester to measure the grounding resistance. Power may only be applied after confirming that the requirements are met, to prevent electric shock, equipment malfunction, or measurement errors caused by poor grounding.

2.1.3 Contraindications for the Procedure

Before wiring, inspecting, or maintaining the equipment, you must turn off the circuit breaker on the back of the equipment and disconnect the main power supply. Confirm that there is no residual voltage before proceeding;

Do not operate the equipment’s power switch, touchscreen, or instrument buttons with wet hands to avoid the risk of electric shock;

Do not place any foreign objects (such as tools or paper) inside the electrical control cabinet to prevent dust or foreign objects from causing short circuits or damaging components;

Do not plug in or unplug power cords or signal cables while the equipment is running to prevent short circuits that could damage the controller or electrical components.

2.2 Operational Safety

2.2.1 Test Specimen Requirements

The equipment must not be used for testing flammable, explosive, toxic, or highly corrosive substances (such as alcohol, gasoline, strong acids, strong alkalis, etc.). Since the equipment is not equipped with explosion-proof devices, such substances may cause fires, explosions, or corrosion of the equipment;

If the test specimen generates heat (such as during power-on testing of electronic components), an external, independent power source must be provided for the specimen. Do not use the device’s own power supply directly to avoid overloading the device’s circuitry;

The sample volume must not exceed 80% of the test chamber’s capacity, and the weight must not exceed the specified load capacity of the shelves (30 kilograms per shelf) to prevent deformation of the shelves or disruption of the temperature cycling process.

2.2.2 Operational Safety

While the equipment is in operation, non-professionals are prohibited from disassembling or repairing it. In the event of a malfunction, contact after-sales service personnel or operate the equipment only under the guidance of a technician;

Avoid opening the chamber door as much as possible during the test. Opening the door when the temperature is extremely high or low may cause the operator to suffer burns or frostbite, and may disrupt the temperature equilibrium inside the chamber, thereby affecting the test results. If it is necessary to open the door, wear heat-resistant gloves and safety goggles, open the door slowly, and wait until the temperature inside the chamber has stabilized before proceeding;

Do not set the temperature above the range specified for the equipment; exceeding the temperature limit may cause the heating element to burn out or even result in a fire;

If the equipment triggers an alarm (the touchscreen automatically switches to the alarm code screen), immediately stop the test and troubleshoot the issue (see “Chapter 7: Troubleshooting and Resolving Common Issues”). Do not force the equipment to restart; operating the equipment before the fault is resolved may cause further damage.

2.2.3 Prohibited Conduct

Do not open the control cabinet door while the equipment is running to avoid touching internal high-voltage components and causing an electric shock;

Do not disassemble core components such as the temperature sensor (PT100 platinum resistance thermometer) or heating elements without authorization. Modifying the equipment will void the warranty and may cause safety incidents;

Do not place heavy objects (such as tools, accessories, etc.) on top of the device to avoid damaging the device panel or impeding heat dissipation;

Do not pile flammable items (such as cardboard boxes, plastic wrap, etc.) around the equipment. Keep the equipment’s ventilation openings clear to prevent the risk of fire.

2.3 Environmental Safety

2.3.1 Installation Requirements

The equipment must be installed in an air-conditioned room where the ambient temperature is maintained between 5°C and 25°C and the relative humidity is ≤85%. If the ambient humidity is high, condensation may form near the equipment door and test ports; in such cases, improve room ventilation or use a dehumidifier;

The installation site must be free of high concentrations of dust, corrosive gases (such as sulfur dioxide and chlorine), and flammable or explosive atmospheres. Direct sunlight on the equipment is prohibited to prevent corrosion of the equipment housing and aging of electrical components;

Keep the device away from areas with significant fluctuations in ambient temperature, such as near vents and doorways, to prevent these fluctuations from affecting the device’s temperature control accuracy.

2.3.2 Space Requirements

The distance between the equipment enclosure and the wall, as well as surrounding fixtures (such as other test equipment and shelving), must be at least 1500 mm to ensure unobstructed ventilation at the equipment’s cooling vents (rear and sides);

At least 2000 mm of space must be left at the equipment door opening to ensure the door can be opened in any direction, facilitating the placement and removal of samples;

2.3.3 Horizontal Placement

The equipment must be placed on a level surface. Use a spirit level to ensure the equipment is level: Place the spirit level on the top surface of the equipment and make sure the bubble is centered. Note: The height of the following types of legs must be adjusted to ensure the test chamber is level:

Figure 5.1

If the equipment is tilted, it may compromise the structural stability of the test chamber, cause uneven temperature distribution inside the chamber, or even result in poor door sealing, thereby affecting test results and the equipment’s service life.

2.4 Other

For matters not covered in this manual, please proceed with caution or contact us.

3. Preparations Before the Test

3.1 Connecting the Power Cord

See 2.1.1.

3.2 Sample Placement

For sample restrictions, see Section 2.2.1.

Note: If the sample requires the use of a cable, please reseal the side opening on the outside of the test chamber with a rubber plug, as shown in the figure below:

Figure 6

Samples must not come into contact with the inner walls of the test chamber; temperature probes must not be touched or covered; and airflow channels must not be obstructed. Samples must be securely fastened and must not move during the test.

3.3 Closing the Cabinet Door

Make sure the box door is closed and the latch is securely locked. If it is a double door, press and lock the left door first, then press and lock the right door.

3.4 Starting Up the Test Chamber

3.4.1 Turn on the power to the test chamber

Press the “Power” button on the control panel on the front of the device. The touchscreen program will enter standby mode. Ensure that there are no alarms in the program; if there are any alarms, refer to Chapter 7 for troubleshooting.

4. Program Operation via the Touchscreen of The High And Low Temperature Chamber

4.1 Introduction to the Main Screen

The system automatically enters the monitoring screen when it starts up. Click “MAIN” in the upper-right corner to access the main screen.

Figure 7

From left to right and top to bottom, they are: ① Curve display; ② Monitoring screen; ③ Operation settings; ④ Program group settings; ⑤ Scheduled settings; ⑥ Display settings.

Figure 8

4.2 Operation Settings

Go to the “Operation Settings” screen. ① Select the test operation mode: FIX (fixed value) or PRO (program); ② Set the test completion action: no action or return to ambient temperature. If you want the system to automatically return to ambient temperature, set the ambient temperature range.

Figure 9

4.3 Appointment Settings

Go to the “Scheduled Settings” screen. ① The left column displays the current time; ② in the right column, enter the scheduled time. Then press the “RESERVE” button on the far right until it turns red—this confirms the schedule has been set, and the test chamber will automatically begin the test at the scheduled time.

Figure 10

4.4 Display Settings

Go to the “Display Settings” screen. ① Select the display language; ② Power-off recovery mode (Stop: After a power failure during operation, the system returns to the “Stop” state when power is restored; Cold Start: After a power failure during operation, the system restarts from the first segment when power is restored; Hot Start: After a power outage interrupts operation, the system continues from the segment where operation was interrupted before the outage, restoring the system to its pre-outage state when power is restored).

Figure 11

4.5 Fixed-Value Operation (Single Temperature and Humidity Point Test)

4.5.1 Accessing the Fixed-Value Settings

Select “Fixed Value” in “Operation Settings.” Go to the “Monitoring Screen,” then click the “Settings” button on the right to open the “Fixed Value Settings” screen.

Figure 12

4.5.2 Parameter Settings

Figure 13

① Temperature Setting: Enter the target temperature (see Section 1.1 for the configurable temperature range).

② Temperature ramp rate: Unless a specific ramp rate has been customized, use the default value of 0. The test chamber will operate using the automatic ramp rate.

③ Timed Operation: Enter the test duration (e.g., 2H; range: 0–9999H); when set to 0, the test must be stopped manually.

④ Wait Setting: If the wait function is selected, the test time will not begin until the test chamber reaches the set temperature. You must also set the wait tolerance (the test is considered complete if the temperature falls within this tolerance range) and the wait time (if the test chamber has not reached the set temperature by the end of the wait time, the test time will automatically begin).

4.5.3 Starting the Calibration Test

After verifying that the parameters are correct, return to the monitoring screen and click the “Run” button in the lower-right corner.

Figure 14

4.6 Program Operation (Multi-Stage Temperature Cycling Test)

4.6.1 Program Group Settings Screen

① Program number: You can set up to 100 programs, numbered 1 through 100, ensuring no numbers overlap with existing programs; ② Enter the program name; ③ Edit the program; ④ Set the loop; ⑤ Set the wait time.

Figure 15

4.6.2 Accessing the Program Editing Screen

① Test segment number; each program can have up to 99 test segments; ② Temperature setting; ③ Test duration setting;④ The relay is set to automatic operation; no changes are needed to the parameters here; ⑤ Switch between segment numbers; ⑥ Insert or delete a segment; ⑦ Number of segments to run in this program. For example, if you only want to run the first four segments of this program, enter 4. Please enter the correct number; otherwise, the program will not run properly; ⑧ Return to the program group settings screen.

Figure 16

Example: If you need to perform the following tests: Step
1: Temperature -20°, test duration 3 hours;
Step 2: Temperature 150°, test duration 5 hours. The

settings should be:

NO.	01	02	03	04	05 …
Temperature	-20°		150°		0
Time	0.01.00	3.00.00	0.01.00	5.00.00

NO 01: Transition phase—the time required to reach the target temperature.
NO 02: Actual test duration: 3 hours.
NO 03: Transition phase—the time required to reach the target temperature.
NO 04: Actual test duration—5 hours.

Note 1: For each identical temperature and humidity setting, two phases must be configured: the first is the transition phase—the time required for the test chamber to reach the set temperature—and the second is the test duration at that temperature.

Note 2: In the examples above, the transition phase was set to only 1 minute. The equipment has a wait function; even if the set time is short, the equipment will reach the set value before proceeding to the next phase. This setting minimizes the equipment’s preparation time, thereby saving test time.

4.6.3 Loop Settings Screen

① Number of loops for the current program; the default value is 1, meaning the test stops immediately after the current program is completed; ② Linked program number; this specifies whether the test will automatically skip to another program to continue testing after the current program is completed. Enter 0 if this is not required; ③ Loop mode for the current program’s test segments; the default value is 0 for all segments, meaning the test does not repeat and proceeds sequentially from the first segment to the last.

Figure 17

Example: The figure below means: After the current program has been run twice, it will automatically proceed to Test Program 3 to continue testing.

Figure 18

The diagram below illustrates that the current test sequence for the program is 01>02>03>04>05>03>04>05>02>03>04>02>03>04>05>06>07…
meaning testing begins with the first segment.sections 3 through 5 are repeated twice, followed by sections 2 through 4 being repeated twice, and then the remaining test sections are completed in sequence.

Figure 19

Based on the logic above, you can configure the program’s test parameters to meet your own testing requirements.

4.6.4 Wait for the Settings Screen

① Select “ALL” to enable the wait function for all test segments; ② Wait zone error value; ③ Maximum wait time.

Figure 20

4.6.5 Boot Sequence Test

After verifying that the parameters are correct, return to the monitoring screen and click the “Run” button in the lower-right corner.

4.7 Test Operation and Monitoring

4.7.1 Monitoring Screen

The monitor screen displays the set temperature and the current actual temperature.

4.7.2 Real-Time Fault Monitoring

If a fault occurs, the touchscreen automatically switches to the “Real-Time Fault Display Screen.”

Check the error codes and refer to Chapter 7 for troubleshooting and resolution; click “Mute” to turn off the buzzer, and click “Reset Errors” once the issue has been resolved.

4.7.3 Viewing and Exporting Curves

Tap the “Curve Display” screen on the main screen to view the real-time temperature curve.

Insert the USB drive, click “Download,” and the curve data will be saved to the USB drive in CSV format (which can be opened and analyzed on a computer).

Tap “Clear History” (press and hold for 5 seconds) to delete old curve data (proceed with caution).

5. Post-Test Procedures

5.1 Equipment Shutdown Procedures

5.1.1 Program Termination

If the program ends normally: The device operates according to the “Program End Mode” (e.g., “Return to Ambient Temperature,” automatically cooling down to the set ambient temperature range).

To stop the process midway: Click the “Stop” button on the monitoring screen, and the device will enter standby mode.

5.1.2 Power-Off Procedures

Verify that the device is in standby mode (not running), then turn off the power switch on the device’s control panel.

Turn off the main power switch.

5.2 Sample Removal and Handling

Wear gloves rated for high and low temperatures (even if the sample has “returned to room temperature,” it may still retain residual heat), open the chamber door, and slowly remove the sample.

Inspect the condition of the samples (e.g., appearance, performance) and record test data (temperature, humidity, time, changes in the samples).

If there is any liquid residue on the sample, wipe it clean with a lint-free cloth to prevent contamination of the work area.

5.3 Equipment Cleaning

Cleaning the Inner Chamber: Wipe the inner walls and shelves of the chamber with a lint-free cloth dampened with alcohol to remove any residual sample stains (do not spray water or alcohol directly onto the surfaces).

Cleaning the Refrigerator Door: Wipe down the door gasket (to remove dust) and check that the gasket is not deformed (if there are stains, wipe them off with a damp cloth).

Cleaning the Outer Case: Wipe the equipment casing with a dry cloth to remove surface dust (do not use gasoline or organic solvents, to prevent the paint from peeling).

Cleaning the Touchscreen: Wipe with a dry cloth to remove fingerprints and ensure touch sensitivity.

5.4 Test Records

Fill out the equipment usage log, recording the following information: test date, program group, sample name, runtime, any malfunctions (if applicable), and operator.

Organize test data (such as graphs and sample reports) and file them for safekeeping.

6. Daily Maintenance and Care of Equipment

6.1 Regular Cleaning and Maintenance

6.1.1 Routine Cleaning (After Each Test)

Maintenance Projects	Maintenance Procedures	Important Notes
Chamber Liner	Wipe with an alcohol-soaked lint-free cloth to remove stains	Do not wash with water; avoid exposing electrical components to moisture.
Sealing Strip	Wipe with a dry cloth and check for any deformation or damage.	If the rubber seal is worn out (and no longer seals properly), contact customer service to have it replaced.
Touchscreen	Wipe with a dry cloth to remove fingerprints and dust	Do not scratch the screen with sharp objects.
Ventilation Opening	Wipe off surface dust with a dry cloth and ensure proper ventilation.	Do not block the ventilation openings (to prevent overheating)

6.1.2 Regular Cleaning

Maintenance Projects	Maintenance Cycle	Maintenance Instructions	Objectives and Requirements
Temperature Sensor	Monthly	Use a soft-bristled brush to remove dust from the sensor surface	Measurement accuracy within ±2°C/±3% RH
Ground Resistance	Every 3 months	Grounding Resistance Tester Inspection	Ground resistance ≤ 50 Ω
Electrical Components	Every 6 months	Open the control cabinet door and check that the relays and terminal blocks are secure.	No oxidation or loose connections; the circuit breaker is functioning normally.

6.2 Long-Term Deactivation for Maintenance (Deactivated for More Than 1 Month)

6.2.1 Disabling Preprocessing

After completing all tests, turn off the power and unplug the unit as described in 5.1.2;

Thoroughly clean the equipment (inner tank, outer casing, and electrical cabinet);

Open the door of the unit and allow the inner chamber to air out and dry naturally (to prevent mold growth);

Remove all samples and shelves (if any) from the equipment and store them separately.

6.2.2 Maintenance During Downtime

Power on the unit at least once a month (for 30 minutes, to allow the circulation fan and controller to run) to prevent components from becoming damp;

Inspect the exterior of the equipment to prevent dust buildup; you may cover it with a dust cover (made of breathable material);

Inspect the storage environment to avoid humidity, high temperatures, or corrosive gases.

6.2.3 Pre-Reactivation Checks

Remove the dust cover and clean the equipment;

Check that the power lines and grounding are in good working order;

After turning on the power, check whether the controller, fan, and heating system are operating normally;

Conduct one short-term fixed-condition test (e.g., 50°C for 30 minutes) to verify that the equipment is functioning properly before proceeding with the formal test.

7. Troubleshooting and Resolving Common Problems

7.1 Touchscreen Alarms

Troubleshooting Codes	Possible Causes	Solution
PT1: Temperature Sensor Malfunction	The PT100 probe is faulty; its resistance at room temperature is 110 Ω; a point on the PLC module is faulty; the PT100 wiring is loose.	Replace the PT100 probe; repair or replace the PLC module; rewire
X2 Temperature Control Over-Temperature Protection	Corrosion at the connection points or exposure to water; uncontrolled heating, resulting in an abnormal rise in temperature; the motor is not running, preventing heat from escaping from inside the heating element; the impeller has fallen off, preventing heat from escaping from inside the heating element	Clean or rewire; check the solid-state output; check whether there is 220V voltage between the red and yellow wires of the motor; if there is no voltage, replace the motor; if there is voltage, replace the capacitor; reinstall the impeller
X3 Test Chamber Overtemperature Protection	The over-temperature protection setpoint is lower than the controller’s setpoint	1. Adjust the over-temperature protection setpoint to match that of the controller.

7.2 Controller-Related Faults

7.2.1 Controller Without a Digital Display

Fault Symptoms	Possible Causes	Solution
The controller screen is black; there is no display.	1. The power plug is not properly connected; 2. The power outlet has no power, or there is a missing phase in the three-phase power supply; 3. The wiring at the controller’s power supply terminals has come loose; 4. Internal controller malfunction; 5. The control cabinet door is open, causing the power circuit breaker to trip.	1. Plug the power cord in securely; 2. Check the power outlet and use a multimeter to verify that the three-phase power supply is normal; 3. Turn off the main power, open the electrical cabinet, check the wiring at the controller’s power supply terminals (e.g., 24 VAC), and retighten the connections; 4. Contact the manufacturer to repair or replace the controller;5. Close the control cabinet door, reset the circuit breaker (inside the control cabinet), and verify that it has closed.

7.2.2 The controller displays garbled characters or the numbers flicker

Fault Symptoms	Possible Causes	Solution
The display shows garbled characters or is unstable	1. Loose connection between the controller and the sensor; 2. The platinum resistance thermometer (temperature sensor) is damaged or has a poor solder joint; 3. Significant power supply interference (e.g., high-power equipment nearby); 4. Internal controller malfunction	1. Disconnect the main power supply, inspect the sensor terminals, and retighten them; 2. Replace the platinum resistance sensor (model PT100, 3-wire system, wire resistance ≤ 10 Ω), and resolder it; 3. Eliminate power supply interference (e.g., keep the device away from high-power equipment and use a regulated power supply);4. Contact the manufacturer to repair or replace the controller

7.3 Heating System Malfunctions

7.3.1 The unit is not heating or cooling

Fault Symptoms	Possible Causes	Solution
No heating	1. Over-temperature protection activated (buzzer alarm); 2. Set temperature is lower than the current actual temperature; 3. Solid-state relay failure; 4. Heating element failure; 5. Platinum resistance open circuit (no signal from the sensor); 6. Heating circuit fuse blown	1. Check the over-temperature protection setpoint, reset it (to 20°C higher than the test temperature), and press the [Fault Reset] button; 2. Reset the temperature (to a value higher than the current actual temperature);3. Disconnect the main power supply and use a multimeter to test the solid-state relay; replace it if damaged; 4. Measure the resistance of the heating element (normally several tens of ohms); replace it if damaged; 5. Inspect the platinum resistance wire connections and replace any open-circuit platinum resistors; 6. Replace the heating circuit fuse (4 A).
Not cooling	1. The cooling switch is not turned on; 2. The compressor has not started; 3. There is a refrigerant leak	1. Go to “Operation Settings” and turn on the cooling switch; 2. Check the compressor power supply and phase sequence, then wait 3–5 minutes before restarting; 3. Contact customer service to locate the leak and recharge the refrigerant.
Slow cooling	1. Insufficient refrigerant; 2. Clogged condenser; 3. Excess moisture in the chamber	1. Top off the refrigerant (to the amount specified for the equipment); 2. Clean dust from the condenser; 3. Dry the moisture from the chamber before lowering the temperature

7.3.2 Uncontrolled Heating (Continuous Rise in Temperature)

Fault Symptoms	Possible Causes	Solution
The temperature exceeds the set value and continues to rise	1. The temperature setpoint is too high (exceeds the equipment’s upper limit); 2. The solid-state relay is stuck (cannot open); 3. The platinum resistance sensor is shorted (abnormal sensor signal); 4. Controller malfunction (cannot output a stop signal)	1. Immediately turn off the main power supply and reset the temperature; 2. Replace the solid-state relay; 3. Inspect the platinum resistance thermometers and replace any that are shorted; 4. Contact the manufacturer to repair or replace the controller

7.4 Abnormal Operating Conditions and Malfunctions

7.4.1 The Circulation Fan Is Not Running

Fault Symptoms	Possible Causes	Solution
The fan is not rotating and is silent.	1. The fan’s power supply wiring has come loose; 2. The fan’s overcurrent protection has tripped (thermal relay tripped); 3. The fan motor is damaged; 4. The controller is not sending a signal to start the fan	1. Turn off the main power supply, check the fan’s terminal connections, and retighten them; 2. Reset the thermal relay (inside the electrical cabinet) and check whether the fan is jammed; 3. Test the fan motor’s resistance (which should normally be several tens of ohms); if it is damaged, replace it; 4. Check the fan control parameters on the controller and contact the manufacturer for troubleshooting.

7.4.2 Poor Cabinet Door Seal (Temperature Leakage)

Fault Symptoms	Possible Causes	Solution
Significant temperature fluctuations during operation; slow heating	1. The door gasket is worn or damaged; 2. The door hinges are loose, causing the door to be crooked; 3. The door latch is loose and does not close securely	1. Replace aged or damaged weatherstripping; 2. Adjust the cabinet door hinges and tighten the screws to ensure the door is plumb; 3. Adjust the position of the latch to ensure the weatherstripping is pressed tightly against the door when it is closed.

7.5 Communication Failure (PLC No Response)

7.5.1 Communication Interruption (Screen displays “PLC no response”)

Fault Symptoms	Possible Causes	Solution
Communication between the touchscreen and the PLC has been interrupted; control is not possible.	1. The communication cable (RS-485) is loose or disconnected; 2. The communication cable is damaged (e.g., broken or shorted); 3. PLC power failure; 4. Mismatched communication parameters (e.g., baud rate, address)	1. Disconnect the main power supply, inspect the RS-485 communication cable terminals, and retighten them; 2. Replace the damaged communication cable (use shielded cable to reduce interference); 3. Check the PLC power supply (e.g., 24V) to ensure it is functioning properly;4. Check the communication parameters (baud rate, address) between the controller and the PLC to ensure they match, and contact the manufacturer for guidance on adjustments

Appendix: Electrical Schematics