CPU 1516-3 PN/DP on a palletiser, TIA V16. The ERROR LED started flashing red last week and hasn't stopped, but the machine runs, the HMI runs, nothing is stopped.
The diagnostics buffer has the same entry hundreds of times:
"Area length error when reading. Global DB, DB number 120, byte address 4000. Block FC 45. Programming error."
Words may be slightly off, I'm reading it off a photo. I went online and did a STOP and RUN, the LED goes off and comes straight back, and a power cycle does the same. The site electrician says the CPU is faulty and wants to order one, and I can't explain the LED well enough to talk him out of it.
Is there a way to clear it without stopping the machine? Could someone explain what DB120 byte 4000 is telling me, so I've got something to say to him?
Not faulty. That entry tells you the block and the byte offset, so it's a programming error, not hardware. What's in DB120 at byte 4000? An array, and what's its length?