SD card red light

We had a leak which got on the plc compactlogix 1769 l36erm. SD card light is red. What does this mean?

From the manual:


https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1769-um021_-en-p.pdf


Table 46 - SD Card Activity (SD) Status Indicator


Off - There is no activity to the SD card.
Flashing green - The controller is reading from or writing to the SD card.

Flashing red - The SD card does not have a file system


Don't see any indication of Solid RED; I would equate that to a solid RED OK light which is processor death.

Do these plcs have batteries? I tried going online and it says "no program on controller". Im thinking the battery died and lost the program...

Just read it doesnt have a battery. Our other plcs (the same model) have an SD card but the light is black. Is it being used? Im just confused how the program got wiped. FYI the SD light is black now not red.

MattMatt9 said:

Just read it doesnt have a battery. Our other plcs (the same model) have an SD card but the light is black. Is it being used? Im just confused how the program got wiped. FYI the SD light is black now not red.

Click to expand...

Oh, well then that's a different story. I guess my biggest comment is that the SD card itself does not store ANY program information on it. It is used soley for backup/restore/storage of auxiliary data; so the fact it is flashing (or not) should have no impact on your program.


If you in fact lost your program then the processor itself took some damage independent of the SD card; you can run that processor without the SD card present and still have a program, retentive memory, etc...


I do also know of some bugs that will wipe a L36's memory if there are a specific amount of power cycles in a given time frame; can you just reload the program then?


*edit* also the L36 does NOT have a battery

If the SD card doesnt store the program data then what keeps the program when the power is cycled? Thats what i thought the battery did was hold the data when power is cycled. If the SD card isnt doing that then what prevents it from losing its data?

ControlLogix and CompactLogix from the L7x platform onward, including your 1769-L36xx, have an onboard capacitor and onboard nonvolatile memory. That nonvolatile memory is separate from the removable SD card.

When the controller powers down, the capacitor runs it for a few seconds and the OS saves the user program and all the active variables to NVRAM. That's what the controller boots from most of the time.

Every ControlLogix/CompactLogix equipped with removable memory checks that device at boot-up for instructions on whether to load from removable memory, or to default to loading from nonvolatile memory. If the nonvolatile memory and the SD card were both corrupted, you would get a solid red indicator for the SD card and an "empty" controller running only the Logix OS, where the user program has been cleared because it failed a checksum at boot.

Your post says you "had a leak which got on the CompactLogix", which suggests that it suffered physical or electrical damage. Take everything out, spend some time rinsing and swabbing with isopropyl alcohol, and try reassembling and restarting once it has dried.