A panel with USB trend logging reads the whole stick before it finishes starting, so a large stick can hold it on Initializing for 10 to 15 minutes even when freshly formatted and empty. Pulling the stick starts the panel but stops logging and raises RTE-004. The repair is a 2 GB or smaller stick formatted FAT.
The stick is the problem, and its capacity is the number that matters. A panel with trend logging set to a USB stick reads the entire stick before it finishes starting. In one reported case, an 8 GB stick held a panel on its "Initializing" screen for 10 minutes on the first power cycle and about 15 minutes on the next, and the stick was freshly formatted and empty at the time. Pull the stick and the same panel starts promptly, then reports it has no stick to log to and shows RTE-004 on the main screen. The repair is small media: a small stick formatted FAT starts the panel promptly and keeps the log writing.
What each symptom tells you
- The panel sits on "Initializing" for 10 minutes or longer with the logging stick inserted. The panel is scanning the whole stick before startup finishes, and the wait grows with the stick's capacity.
- The panel starts promptly once the stick is removed. The project and the panel hardware are fine; the media is the variable.
- The stick is slow even freshly formatted and empty. The scan reads the drive itself, so the number of files on it changes nothing.
- After starting without the stick, the panel reports it has no USB stick to log data to, and RTE-004 appears on the main screen. That is the logger missing its target: the panel runs, with logging down.
Why the stick sets the startup time
The panel's documentation sets two rules for the media. Its port is USB 2.0, and the stick must be formatted FAT or FAT32, with FAT the recommended one of the two; the help file prints that on page 2-23 of the edition current at the time. Sticks with non-standard controllers can fail outright, and which USB drives work in an HMI panel covers that separate check.
The startup cost sits on top of the format rule: with logging enabled, the panel reads the entire stick before startup completes, so a big stick carries a long scan and a small one a short one. The field numbers behind that are blunt: the small stick starts promptly, the big one in the reported case held its panel 10 to 15 minutes. Slow startup on industrial panels is common enough that reports exist of panel computers taking around 30 minutes to boot and then running normally; whenever the wait sits between power-up and the operating screen, look first at what the panel has to read before it starts.
Check the stick before you change the project
Leave the trend graph and the logging option alone until the media is cleared. Work this list:
- Write down the stick's capacity, its file system, and whether it was inserted at power-up.
- Time one full startup with the stick in and one with it out. Record both numbers.
- Confirm the project still carries its logging option, "Log Data to USB Stick" in the reported project, running software version 2.75.
- Copy any log data you need off the stick before you format or replace it. The same discipline applies when saving alarm history to a USB stick: get the data off first.
- If the panel reports no stick at all, even one it read yesterday, that is a different fault: start with a USB drive the panel does not recognize.
Example: a logging stick that holds the panel 15 minutes
The inputs, all from the reported case:
- Logging stick: oversized for the job, freshly formatted, empty.
- Project: trend logging to USB, option "Log Data to USB Stick", software version 2.75.
- First power cycle: about 10 minutes on "Initializing".
- Second power cycle, same stick: about 15 minutes to reach the operating screen.
- Same panel with the stick removed: starts promptly, then reports the missing logging target and RTE-004.
The rule in words: the panel reads the whole stick before startup completes, so the wait tracks the stick's capacity. Take the worst case, 15 minutes, and assume the scan time scales with capacity. A stick one quarter the size then takes one quarter of the time:
15 min × 0.25 = 3.75 min
The measured field result beats that estimate: the small stick starts the panel promptly, and the standing guidance is to stay small. The decision falls straight out: with a stick at the reported size or larger, plan on 10 to 15 minutes of "Initializing" at every power-up; with one a quarter of that size or smaller, the wait is short enough that operators will not build a startup procedure around it.
The fix, step by step
- Copy the log data off the current stick to the computer.
- Get a stick at most a quarter of that capacity, with a standard controller.
- Format it FAT on the computer, and confirm the file system shown in the drive's properties.
- Insert the stick before power-up. The panel scans it during startup, so it has to be in place at power-on.
- Power the panel up and time the run to the operating screen.
- Open the trend log and confirm rows exist with times after this startup. Confirm the missing-target message and RTE-004 are gone.
- Power cycle once more and time it again, to catch an intermittent detection problem.
- Write the stick's capacity and format into the maintenance records so the next replacement matches.
One safety note: if this panel is the operator's window on a running machine, run both startup tests between cycles, with the machine idle.
Running without the stick gets you through the shift
Pulling the stick does start the panel, and there will be a shift where that is the right call. Know what you are choosing: the logger has no target, the panel announces it at startup, and RTE-004 sits on the main screen. Tell the operators logging is down. That state is for the day; the small FAT stick restores the log. For routine media changes once logging is healthy, safe removal with an eject button is the cleaner habit to teach in place of pulling sticks at power-up.
How you know it is fixed
Three checks, all with the stick installed: the recorded startup time is short and repeats on the second cycle; the trend log holds rows written after startup; the missing-target message and RTE-004 stay away. When all three hold, the original 10 to 15 minute wait was the media, and the case closes with the stick's capacity and format in the maintenance file.
Recommendation: Put USB trend logging on a 2 GB or smaller stick formatted FAT, inserted before power-up, and keep one spare formatted the same way. Treat any stick of that reported size or larger as a 10 to 15 minute startup penalty at every power cycle. If a panel must run before the spare is ready, pull the stick, tell the operators the log is down, and fit the small stick at the next break.
Questions
Why is an empty logging stick still slow?
The startup scan covers the stick's whole capacity, not the files stored on it. The oversized stick in the reported case was freshly formatted and empty and still needed about 15 minutes. Deleting files or reformatting the same stick leaves the capacity where it was, so the wait comes back at the next power cycle. Only a smaller stick shortens the scan.
Can the logging stick be FAT32 instead of FAT?
FAT32 meets the documented format rule, but the panel's help file recommends FAT, and the computer side argues the same way. The format tool built into Windows stops offering FAT32 above 32 GB, so a large stick would need third-party tools before it even meets the panel's rule. A small stick formatted FAT sidesteps both problems.
What does RTE-004 mean in this startup?
It travels with the missing logging target. The panel booted without the stick the project expects, so it announces that the log destination is absent. Record the exact wording and the moment it appears. Once the small FAT stick is installed and logging resumes, that startup message goes away on a normal power-up.
What if the panel is still slow with a small FAT stick?
Then capacity was not the whole story, and more power cycles will not change it. Stop cycling the panel and collect the software version, the stick's capacity and format, the measured startup time, and the exact on-screen messages. Take that list to the panel maker's support channel; it answers their first questions in advance.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.