UniOP ePAD03/04 Human Computer Interface

Physical compatibility: The opening sizes of the two are similar (MD00 is usually 136 × 96 mm or similar), and the ePAD series can be directly installed on the original cabinet door opening without the need for sheet metal modification.

Communication driver: ePAD supports over 130 types of drivers, covering almost all protocols supported by MD00. But there is one exception: when the MD00 uses a 20 mA current loop interface, the ePAD series cannot directly replace it (the original text states "except when the 20 mA current loop interface is needed"). At this point, it is necessary to install a current loop to RS-232 converter or choose another model (such as the BKDR-46 series supporting current loops).

Engineering migration: MD00 uses outdated programming software (possibly MDTool or early UniOP Workshop), and engineering files need to be manually rebuilt or converted through export/import mechanisms. It is recommended to reconfigure in Designer 6 based on the original screen layout and variable definitions, which usually takes 2-3 days.

Function improvement: Compared with MD00, ePAD series has added functions such as graphic display, scalable fonts, recipe storage, Ethernet options, etc., which can increase data traceability for devices while replacing them.

Common troubleshooting and on-site maintenance

Based on the hardware features and on-site usage experience of ePAD03/ePAD04, the following six types of faults and their handling methods are summarized. Before performing any internal operations, be sure to disconnect the 24V power supply.

Fault 1: After power on, the screen does not display and the LED does not light up

Possible reasons:

The power supply voltage is too low or the polarity is reversed.

Internal self recovery fuse action (such as after output short circuit).

The power module is damaged.

Troubleshooting steps:

Measure the terminal voltage with a multimeter, which should be between 18-30V.

Disconnect all external devices (PLC wires, modules), keep only the power supply, and power on again. If restored, the external short circuit will cause the fuse to operate, and it will automatically recover after cooling.

If there is still no power, replace the power supply or repair it.

Fault 2: No response or delayed response to buttons

Possible reasons:

The button is mechanically stuck (sliding into the label paper and lifting up).

The keyboard membrane is aging or has entered liquid.

The system has entered a password lock state.

Troubleshooting steps:

Check if the physical feel of the four function keys and seven system keys is normal.

Enter the system diagnostic mode (press and hold a combination key while powering on, refer to the user manual for details) to test the keyboard matrix.

Clean the stains on the edges of the button film.

Confirm if there is a password lock, try entering the default password or contact the system administrator.

Fault 3: Communication interruption or data error

Possible reasons:

RS-232/485/422 wiring error or cable too long.

The communication parameters (baud rate, data format) do not match the PLC side.

The optional module used is not installed correctly or the driver is not enabled.

Troubleshooting steps:

Open the current project in Designer and verify the PLC port settings.

Use short distance (<15 meters) direct connection testing to eliminate cable and interference issues.

If using an Ethernet module, check the IP address, subnet mask, and port number.

Use serial port monitoring tools to capture messages sent by HMI and confirm if there are request frames.

Fault 4: Inaccurate real-time clock timing or power failure reset

Applicable model: ePAD03 only (ePAD04 without RTC)

Possible reasons:

The internal CR2430 lithium battery has run out of power (usually with a lifespan of 3-5 years).

Replacement steps:

Disconnect the 24V power supply and open the back cover (pay attention to electrostatic protection).

Find the CR2430 battery holder and remove the old battery.

Install the same model CR2430 lithium battery (with the positive electrode facing upwards) to ensure compatibility with the operating temperature range (industrial grade batteries are required for extended temperature models).

Power on again and enter the system menu to calibrate the date and time.

Fault 5: The screen display contrast is too low or too high

Possible reasons:

The contrast software settings are not appropriate, or the ambient temperature causes LCD characteristics to drift.

Adjustment method:

Find the contrast adjustment slider in the system menu or user interface (via software settings).

If there is no open adjustment option, it can be achieved by adding contrast adjustment variables or key macros in Designer.

If the adjustment is ineffective, it may be due to LCD aging or driver circuit failure, and the display screen needs to be replaced.

Fault 6: Unable to program or transmit data through Ethernet module

Possible reasons:

The Ethernet module did not obtain a valid IP (DHCP is not enabled and static IP is not set).

The firmware versions of Designer and HMI do not match.

The switch or firewall is blocking the required port (default 1024 or custom).

Troubleshooting steps: