Problem with S7-1512C1-PN CPU

Hi All,

I have a problem with the CPU of my PLC. First of all, my PLC is SIMATIC S7-1512C-1PN (6ES7512-1CK01-0AB0). 

One day,  the PLC started doing strange things like activate outputs that shouldn't be activated or doesn't read the inputs so I reset the PLC by turning it off 1 minute and then turning it on again.

And here is the problem:

When the CPU loaded the firmware and tried to connect to the net, it appeared Fault and the CPU started to reboot continuously (Connecting -> FAULT -> Connecting -> FAULT ...). The PLC spent the night turned off and the next day it worked perfectly until now, that has the same problem. Obviusly, I've turned it off, this time for a week, but it hasn't worked. I've tried to delete the memory card and do a factory reset but nothing has worked. In fact, it keeps frozen in the reset screen.

In addition, the run / stop led is turned on in yellow, and the error led and maint led are blinking. I've read the users guide but the diagnostic buffer is empty.

What else can I do to solve the problem?

Thanks in advance for your help.

Hi MMS12,

I would try to load the latest firmware to get the PLC working again.

It is quite understandable - and not uncommon - to try a quick reset in the event of an error. However, as you may have noticed, in some cases the contents of the diagnostic buffer are lost. So a tip from me is to save the diagnostic buffer first and then try a reset.

Kind regards
Stefan

It sounds like a wiring problem that was their all along, or running for an extended period of time with equipment vibration or heat / cool cycles or motion flexing of cabling that caused them.

Try rotating out (removing) the I/O module wiring terminals to eliminate wiring problems.  Then get the PLC to boot correctly so you can connect using TIA Portal.  Review the current diagnostics buffer (save it as previously posted) and replace the firmware again, or upgrade it (preferred).

After the PLC powers up and seems to be cooperating, load the current PLC project to it again to make sure the hardware configuration is correctly loaded.

Then once the PLC is behaving, start rotating I/O module terminals into the modules one at a time while monitoring for proper response.  Once you rotate a module terminals into place and I/O stops behaving correctly, undo that module and continue for the remaining modules - in case there are multiple wiring problems.

Verify also the DC supply earth/GND bonding to the 0V leg is proper and that all enclosure grounds and the mechanical system ground are properly connected (bonded).

MMS12

Hi All,

I have a problem with the CPU of my PLC. First of all, my PLC is SIMATIC S7-1512C-1PN (6ES7512-1CK01-0AB0). 

One day,  the PLC started doing strange things like activate outputs that shouldn't be activated or doesn't read the inputs so I reset the PLC by turning it off 1 minute and then turning it on again.

And here is the problem:

When the CPU loaded the firmware and tried to connect to the net, it appeared Fault and the CPU started to reboot continuously (Connecting -> FAULT -> Connecting -> FAULT ...). The PLC spent the night turned off and the next day it worked perfectly until now, that has the same problem. Obviusly, I've turned it off, this time for a week, but it hasn't worked. I've tried to delete the memory card and do a factory reset but nothing has worked. In fact, it keeps frozen in the reset screen.

In addition, the run / stop led is turned on in yellow, and the error led and maint led are blinking. I've read the users guide but the diagnostic buffer is empty.

What else can I do to solve the problem?

Thanks in advance for your help.