Sounds to.me that either the Emergency Stop button is pressed in or a fuse/breaker for it is open... that would be your hardwired safety interlock signal into the PLC so it's not the PLC. You. End a multimeter and to.trace some.wires.
I'm not sure where you read the alarm, but that sounds like something that would have been written by the machine builder, not one of the alarms built into the PLC.
On the display monitor it shown message A351 - Emergency circuit not fed
And when I'd turn on some machine by clicking on the display monitor, it doesn't works. Seems like the PLC and the machines doesn't connected.
Check whether the power supplies are OK, could be a blown fuse in the control circuit. Is the PLC actually powered up? As suggested above, this sounds more like a control circuit problem than a PLC problem.