The USB log copy that stops after the first day is a trigger problem, not a logging problem. The panel writes one dated log file to its card every day; a momentary pushbutton ends the SYS COPY LOGTOUSB command before the multi-file copy finishes. Change the object to Set On or Toggle On, let the function reset itself, and size Total stored samples to the on-panel review horizon.
When a panel copies one day of trend logs to USB and nothing new arrives, the logging is usually still working. The panel opens a new, date-named log file every day and writes it to its card; what fails is the transfer. In the setup that produced this fault, the pushbutton that triggered SYS COPY LOGTOUSB was set to Momentary On, so the command lived only as long as the press. A copy of a week's daily files runs longer than a press, the command dropped out mid-transfer, and the USB drive kept the first day's file. The correction is to hold the command: change the object to Set On, or to Toggle On, and let the copy function reset the trigger itself when it finishes. The sections below give the symptom list, the checks, the fix, and the arithmetic that sizes the stored-sample limit for this three-pen, 15-minute log.
Why the copy stops after the first day
Two functions run in this setup, and they fail separately. The logging function writes the trend's records to the card, one file per calendar day, named for that date. The transfer function, SYS COPY LOGTOUSB, copies those dated files from the card to the USB drive. A single dated file on the drive is the footprint of a copy that died early; the card behind it can still hold a file for every day. The rollover itself has its own mechanics, covered in how an HMI trend log file rolls over at midnight on USB.
The copy function copies every dated file on the card, not just the newest one. What it needs is a trigger that stays on until the work is done. Momentary On holds the command for the instant of the press, and a multi-file copy outlasts a press. Set On latches the command on, and Toggle On does the same on a toggle-style screen; the copy function resets the trigger when the transfer completes. Set On is the setting that cleared this fault, and Toggle On works the same way.
A copy planned once a week is seven dated files by construction. That is exactly the workload a momentary press loses.
Symptoms and what each points to
- One dated file on the USB drive, a dated file for every day on the card. The trigger object is Momentary On. That pair of observations is the signature of this fault: logging healthy, transfer dying partway.
- No new dated file on the card after midnight. The logging path itself. Check that the save destination still points at the slot holding the card, CF1 in this setup, and that the card has free space and no bad sectors.
- The copy runs but the drive ends up empty, or the panel ignores the drive. Test the drive before touching the project; the drive test for a panel that skips a USB stick sorts a bad drive from a bad trigger.
- The panel takes longer and longer to start. The review history, not the daily logs. The panel keeps the on-panel trend history in a binary file on the card and reads it into memory at power-up, so a large Total stored samples setting grows the file every start must load. The example below sizes that setting.
Checks before you change anything
- Confirm the trend's save destination points at the slot the card sits in. The failing setup saved to CF1.
- Pull the card in the machine's documented service state and read it on a PC with a card reader. One dated file per day on the card means the logging function and its daily rollover work, and no Event Manager change is needed.
- Check free space and card condition while the card is out. A full card blocks new records, and a card with bad sectors drops them.
- Leave three shortcuts alone. Reducing Total stored samples shrinks the on-panel review depth and leaves the copy untouched. Formatting the card to FAT32 cleared the files and the identical fault returned, so treat a format as scheduled maintenance with a backup first; keep a master copy of the project before any erase. The fault also reproduced with firmware 2.51 installed, so make the button change first and weigh a firmware update separately.
Set the copy button to hold
- Open the project and find the object assigned to
SYS COPY LOGTOUSB. - Change its object type from Momentary On to Set On. Where the screen already uses a toggle-style pushbutton, Toggle On is the matching choice; both hold the command on, and the function resets the trigger when the copy finishes.
- Deploy the revised project through your site's approved change procedure.
- Run the copy with the USB drive the operators actually use, and wait for the function to reset before pulling the drive.
- Verify across a date change. Let logging cross midnight, look for the new dated file on the card, run the copy again, and compare file names and counts on card and drive. Repeat with at least two dated files on the card so the run exercises the multi-file copy that a momentary press loses.
Example: three pens at a 15-minute interval, copied weekly
The inputs, all from the setup in question:
- Logging interval: 15 minutes.
- Pens: 3 values on one trend graph, one record per pen per interval.
- Total stored samples: 65535, the configured maximum.
- Copy cadence: once a week to USB.
- Card: 1 GB CompactFlash in slot CF1.
Every count scales with the interval. For on and off states, a 10-minute interval is usually enough.
The rule in words: multiply the intervals in a day by the pens to get the records written per day, then divide Total stored samples by the positions one day uses to get the review horizon in days.
The arithmetic:
- A day holds 1440 min ÷ 15 min = 96 logging intervals.
- Records per day: 96 × 3 = 288.
- A week between copies: 7 × 288 = 2016 records, waiting in 7 dated files.
- Review horizon: 65535 ÷ 96 ≈ 682 days of 15-minute positions, about 22 months. Counting one stored sample per pen instead of per interval gives 65535 ÷ 288 ≈ 227 days, about 7 months.
The result: months of review depth on the panel against a 7-day copy cycle, under either reading of the counter. The decision: a 30-day review horizon needs 30 × 96 = 2880 positions, so set Total stored samples near 2880 when operators page back a month at most, and keep 65535 only where the graph genuinely needs that depth. The limit sizes the review; the button's object type fixes the copy.
What to set
Recommendation: change the object that triggers SYS COPY LOGTOUSB from Momentary On to Set On, or to Toggle On where the screen is already toggle-style; wait for the function to reset before removing the drive; and accept the fix only after a copy that crosses midnight with at least two dated files on the card. Set Total stored samples to the review horizon the operators use, about 2880 positions for 30 days at a 15-minute interval, and treat a card format as scheduled maintenance with the project and logs backed up first. Where no dated file appears after midnight, run the card and destination checks first.
The same split, logging path first and transfer path second, holds for most shop-floor screens and boards that keep records on a card: find which function stopped before changing any setting.
Questions
What happens when Total stored samples reaches 65535?
The setup behind this fault never reached the limit, so the end-of-range behaviour went unobserved, and the panel's own documentation is where that behaviour is named. The weekly copy kept fresh dated files moving to USB, and the fault that looked like a storage limit turned out to be the trigger object. Size the limit to the review horizon the operators need and read 65535 as review depth, never as a copy setting.
Why did formatting the card to FAT32 look like a fix at first?
The format wiped the old files, so the first copy afterwards ran against an empty card and looked clean. The identical fault came back, which is what moved the suspicion to the button. Treat a format as maintenance: it erases the project stored on the card and every log file with it, so the backup comes before the erase every time.
Do you have to keep the button pressed until the copy finishes?
No. Set On and Toggle On latch on the first press, and the copy function resets the trigger itself when the transfer finishes, so nobody holds anything. Momentary On is the only one of the three that dies early, because its command exists only for the instant of the press. Where the object is already a toggle style, Toggle On is the closer match.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.