OMRON NT Series HMI Replacement and Maintenance

Connect the computer COM port to HMI port A using XW2Z-S002 cable.

Open the Support Tool and select "PT → PC" to upload existing screen data.

Convert data into a format recognizable by new HMIs (such as NB/NA series). OMRON provides the "NT to NB Converter" tool, which can batch convert NT series screen data into NB series projects, but requires manual adjustment of some objects (such as numerical display and charts).

Attention: If the original NT20 uses the Memory Link system program (non-standard Host Link), the Support Tool needs to install the corresponding system program file, otherwise it will not be able to read the screen correctly.

3.2 Directly copy using Memory Unit (NT-MF261)

The Memory Unit can be used for NT631C/NT31/NT20 (universal), and it is an SRAM memory card that requires battery retention. Usage:

On the source HMI, write screen data to the Memory Unit using the Support Tool.

Insert the Memory Unit into the target HMI, and after power on, the HMI will automatically detect and prompt whether to transfer.

After the transmission is completed, the RUN indicator light flashes (normally on).

The battery life of a Memory Unit is about 5 years, and backup units that have not been used for a long time should have their battery voltage checked before replacement.

3.3 Alternative solutions when unable to read raw data

If the original HMI is damaged and there is no backup, the HMI function can only be inferred based on the on-site PLC program. Common practice:

Monitor the DM and CIO areas in the PLC that communicate with the HMI, and record the numerical changes of each address.

Using the online monitoring function of PLC, trigger the touch switches of the original HMI one by one and record the corresponding PLC bit addresses.

Redraw the screen on the new HMI and write macro programs to simulate the original functions.

System program upgrade and compatibility

The system programs (firmware) of the NT series can be updated through the System Installer tool to support new communication protocols or fix defects.

Version correspondence:

NT31/631 system program version 4. x can only use System Installer V2 (included in Support Tool 4.08 and above). The old version of Installer (V1. x) only supports versions 3. x and below.

The NT20 system program requires the use of System Installer V2.1 (Support Tool 4.8 and above).

Upgrading precautions:

Before upgrading, it is necessary to back up the current screen data, as upgrading the system program may clear the user screen.

System programs of different language versions cannot be mixed. For example, Simplified Chinese system programs can only be installed on NT20-ST121 (B) - EC models and require the purchase of a dedicated version.

After upgrading, communication parameters such as port mode and baud rate need to be reset.

Common system program types (taking NT20 as an example):

Standard version: Supports Host Link, NT Link, C200H direct communication.

Memory Link version: Only supports RS-232C Memory Link protocol (for connecting to PC).

Mitsubishi FX Series Special Edition: Directly connected to Mitsubishi FX Series PLC.

If the original NT20 uses the Memory Link system program, the new HMI must also support Memory Link when replacing it (such as NS series or NB series, which need to be simulated through macro instructions), otherwise direct communication cannot be achieved.

Typical troubleshooting and preventive maintenance

5.1 Touch screen unresponsive or triggered incorrectly

Reason: Aging of touch panel, surface oil stains, calibration failure.

handle:

Clean the screen surface with a neutral cleaner (avoid using benzene solvents).

NT31/NT631 supports 100 level contrast adjustment through the touch panel, or you can try entering the system menu to recalibrate the touch position.

If the touch area deviates by more than 5mm, the touch panel needs to be replaced (accessories can be ordered from OMRON).

5.2 Backlight not lit or darkened

Reason: CCFL backlight lifespan is exhausted (nominal 50000 hours, approximately 5.7 years).

handle:

The backlight of NT20 cannot be replaced (with a lifespan of 50000 hours), and the HMI needs to be replaced as a whole.

The backlight of NT31/NT631 can be replaced (requires disassembly). After replacement, the backlight timer (parameter settings) needs to be reset in the Support Tool.

If the backlight becomes dim but still lights up, you can try adjusting the brightness (NT31 supports 3-level brightness adjustment).

5.3 Communication Failure (No Response or Data Error)

Troubleshooting process:

Check if the cable is intact and if the plug screws are tightened.

Confirm that the HMI port mode is consistent with the PLC (RS-232C/422A/485).

Verify communication parameters: baud rate, data bits (7/8), stop bits (1/2), parity (even/odd/none).

For 1: N NT Link, check if the station numbers of each HMI are duplicated (station numbers are set through memory switches).

Check the "Communication Diagnosis" or error log (if any) in the HMI system menu.

5.4 Low battery voltage alarm

NT31/NT631 has a lithium battery (C500-BAT08) inside, which is used to maintain the clock and some memory table data. When the RUN indicator light flashes orange or the screen displays "BAT", the battery needs to be replaced within 30 days, otherwise data may be lost.