The PLC timing values and the operator message follow separate data paths. Changing a timing operand can correct the process while leaving a static text string in the DM area unchanged. Treat the displayed number as a second configuration item, not as proof of the value used by the control logic.
What must change after the PLC timing is corrected?
First determine whether the NT2S screen displays a live numeric value or fixed text stored in PLC memory. A live numeric object converts a PLC word into digits whenever the screen refreshes. Fixed text stored as character bytes changes only when its assigned DM words are rewritten.
Look at the process behavior or trend first. If the revised timing now controls the equipment correctly but the screen still states the old timing, the control value and message text are independent. Tuning does not fix wiring, and another timing edit does not fix a static message.
The equipment record contains both CPM2C and CMP2C spellings. Read the controller nameplate before selecting a PLC type or making a connection; this procedure uses CPM2C because that is the stated article subject.
Which signal proves where the wrong value originates?
| Signal | Source to inspect | Wrong-value symptom |
|---|---|---|
| Process timing | PLC logic and the words or timer operands used by that logic | The machine sequence still runs for the old interval |
| Message characters | The suspected DM words read by the HMI |
The process uses the new timing, but the screen describes the old value |
| Rendered display | The NT2S screen object and its assigned PLC address | The correct characters exist in memory, but the HMI shows different or garbled text |
Follow the rows in order. If the process timing is wrong, correct and verify the PLC operand before touching message memory. If the timing is right and the message bytes are old, edit the relevant DM words. If the memory is right but the screen is wrong, inspect the HMI address, text length, character order, and screen configuration.
How do you locate the correct DM words?
The message addresses are not identified in the equipment record. Obtain them from the NT2S project when that project is available. Open the applicable screen object and record its PLC address and allocated length. This is safer than changing candidate words on a running machine.
Without the HMI project, connect with CX Programmer, open the Memory Window, enter online monitor mode, and select the text display format. Search for a distinctive fragment of an existing message rather than a common number or short word. Numerous messages are present in this installation, while only seven require additions or changes, so a unique phrase reduces false matches.
Record the raw values and neighboring words before editing anything. PLC data memory is word-oriented, while display text is character-oriented; text commonly occupies character bytes packed into consecutive words. The HMI configuration determines character order, encoding, field length, and the handling of unused characters. The appearance of recognizable text in the Memory Window is the practical confirmation that the selected format and address are correct.
Why might the strings be absent from the uploaded project?
An uploaded PLC program and the live contents of data memory are separate artifacts. A ladder upload can recover the executable logic without placing the current DM message contents into the offline project view. Read the required memory range through the Memory Window or use the applicable memory-area transfer operation.
CX Programmer provides the required Memory Window and text view, so SYSWIN is not a prerequisite for this task. This avoids making the older software, which did not run on the stated Windows 8.1 computer, part of the repair path.
Check transfer direction before using any block operation. An upload reads from the PLC into the engineering workstation; a download writes workstation data into the PLC. Reversing that direction can replace valid live messages with stale offline contents. For seven isolated changes, an online edit is usually the narrower operation, provided the machine is in an approved state and a backup of the original words exists.
How should the text be edited without corrupting adjacent data?
Prove the field boundary before entering replacement text. A string that exceeds its allocated words can overwrite another message or unrelated process data. A shorter replacement can leave trailing characters from the old message unless the remaining character positions are filled using the same convention already present in neighboring messages.
Preserve the observed character packing and termination pattern. If the text view shows swapped character pairs or unreadable symbols, stop editing and compare the raw word view with a known message. That symptom points to the wrong byte order, display format, encoding, or starting address—not bad text that should be rewritten repeatedly.
Watch the address online after a test write. If the entered value immediately reverts, PLC initialization logic, an HMI write, a recipe operation, or another communications client may own that memory. Find the writer before forcing the value again.
What is the safe update and verification procedure?
- Place the equipment in the operating state required by the site procedure for an online data change. Account for the possibility that the HMI will display new text immediately.
- Confirm the PLC and HMI nameplates, including
CPM2CandNT2S-SF123B-EV2, before configuring the connection. - Upload and save the PLC program, then separately capture the relevant
DMrange. Record each original word and its address. - Open the CX Programmer Memory Window, go online in monitor mode, and select text view.
- Find each message address from the HMI project or by matching a distinctive existing phrase. Cross-check the same location in raw word view.
- Determine the allocated field boundary from the HMI object or the established layout of adjacent messages.
- Edit one message first. Keep the replacement within that boundary and reproduce the existing padding or termination convention.
- Write only the required
DMwords. Do not transfer an unrelated memory block. - Display the affected NT2S screen and compare the complete message, including its final characters, with the intended text.
- Recheck the PLC timing behavior. Confirm that no control value or adjacent message changed, then repeat the proven method for the remaining messages.
Monitor the edited words long enough to detect an automatic rewrite. If the values must survive a restart, perform the approved restart test and read them again. A value that returns to its old contents after startup directs the next check to PLC initialization logic, HMI startup writes, recipes, or memory-retention configuration.
FAQ
Why does the NT2S still show the old timing?
The process timing and displayed sentence can occupy different PLC locations. If the machine uses the new interval, update the static characters in the assigned DM words rather than changing the timing operand again.
Why did the PLC upload omit the DM text strings?
The program and live data-memory contents are handled separately. Read the relevant DM range online through the CX Programmer Memory Window or explicitly upload that memory area.
Why does the text appear swapped or garbled in the Memory Window?
The selected text format, byte order, encoding, or starting address does not match the HMI layout. Compare raw words with a known message and prove the character mapping before writing new data.
When should I stop and contact official support?
Stop after read-only checks if the message address cannot be identified, writes repeatedly revert, or the raw words cannot be mapped to known screen text. Do not continue trial writes into an unknown DM range. Contact Omron official support with the confirmed controller and HMI nameplates, the installed CX Programmer version, the backed-up memory range, and the HMI project if available.