It is highly likely that the PLC has transformed from a useful programmable controller to a horrible door-stop, or a overly large paperweight, or what others commonly refer to as a "brick".

That said, if you have someone at your place of learning with electronics repair skills, they may be able to investigate what components have caused this horrible transformation.

Or, you can contact Siemens Repair to see if they are able to perform a repair exchange where they ship you a refurbished certified working S7-1214 AC/DC/RLY and you return this transformed certified non-working "brick" - with a little money exchange and such.

What bothers me is that this is an AC powered PLC with L+ / N / Ground for input power, 24VDC / 0V for RLY output, and it provides a small amount of 24VDC on its own to power simple 24VDC input devices.

Did they apply 0 and 24VDC to the AC input terminals?

Or, did they simply reverse the RLY output terminals?

Or, is the PLC really a DC/DC/RLY (what I suspect)?

Kevin.m

Hello, i have a s7-1200 1214cac/dc/rly.

One of my students connected the "m" ports to 24v and now the run/stop light blinks between the two, error blinks in red and maint blinks in orange.

Link button is always on and rx/tx light doesn't turn on, even if i reset it.

Is the PLC dead?

Please help.