Define the Data Path Before Programming
The evidence does not establish which device will create the USB file, how the HMI communicates with the PLC, or whether the installed HMI configuration supports writing records to USB. Confirm those points in the applicable product documentation before selecting an implementation.
| Item | Confirmed requirement | Decision required |
|---|---|---|
| Text | Entered through the DOP100 HMI | Maximum length, permitted characters, and empty-value handling |
| Storage | USB media | Device responsible for file creation, supported format, and removal procedure |
| Record trigger | Not specified | Manual save, process event, or periodic logging |
Build a Defined Mixed-Data Record
Keep the HMI text and PLC numeric values in separate typed fields while the record is being assembled. Define one record-valid flag and one save request so that a partially edited string cannot be paired with numeric values from a different process state. If the storage device requires a text-based file, serialize the fields only at the file-writing boundary.
Specify the column order, delimiter, decimal separator, text encoding, and rules for delimiters or line breaks entered by the operator. The available evidence does not identify a timestamp source, so include a timestamp only after choosing and validating the responsible clock.
Configure the Logging Sequence
- Create an HMI text-entry field with an explicit length limit and map it to a shared data location accessible to the logging sequence.
- Expose the required PLC numeric values to the HMI through the configured PLC-HMI connection. Preserve each value's data type and document any scaling.
- Define a save command. On its rising event, validate the text and numeric fields, capture one coherent snapshot, and request one file record.
- Configure the device selected as the file writer to append the snapshot to USB media. Use only a file format and USB function explicitly supported by that device.
- Return completion or failure status to the HMI. Do not clear the operator's entry until the write operation reports successful completion.
If the DOP100 cannot perform the required USB file operation, move file creation to another confirmed-capable component.
Verify Record Integrity
Test one record containing valid text and representative numeric values, then inspect the resulting file on an independent reader. Confirm field order, full text retention, signs, decimal placement, engineering units, and that one save command produces exactly one record. Repeat with blank text, the maximum allowed text length, numeric boundary values, and a failed or removed USB device.
Also verify recovery behavior: the HMI must show a failed write, retain unsaved data, and prevent an unconfirmed record from appearing successful. Reconnect the PLC-HMI link and repeat the test to ensure stale numeric values are not silently logged.
FAQ
Confirm those two capabilities before implementing the record sequence.
How do I store text and numeric PLC values in the same USB file?
Capture the HMI text and PLC numbers into one validated snapshot, then serialize that snapshot using a defined column order, delimiter, decimal separator, and encoding. Keep the fields typed until the file-writing step.
How do I prevent duplicate or incomplete USB records?
Trigger logging from a single save event, latch one coherent snapshot, and accept another request only after the writer returns completion or failure. Clear operator data only after a confirmed successful write.