Dear friends,

I have this HW configuration

CPU 1515 connected to +24 VDC,

8 IO cards

1 PS25W

4 IO cards

If PS turns OFF, the CPU goes to STOP.

Is there a way to prevent STOP mode of CPU in this case?

Thanks

Hello,

It seems that you connect external power to CPU with back plane bus.

Please go through the following FAQ and mark sellection "Connection to Supply Voltage L+".

How should you configure the system power supplies for the S7-1500 in STEP 7 (TIA Portal) so that all the connected modules are supplied?

Hope this helps.

bantonio

If PS turns OFF, the CPU goes to STOP.

 Kindly post the diagnostic buffer for the CPU when goes to STOP mode.

Hello bantonio,

When you download your configuration to the CPU, all information includes: type and number of modules stored in memory of CPU. so when you bring the CPU in RUN mode, it has access to all modules on the rail by backplane bus ( if backplane bus has supplied with CPU/PS or CPU and PS) .

In your HW configuration, PS just supplies it,s right hand modules and does not have any relevance with CPU supply voltage.

But, when PS turns OFF, it supplies no bus voltage. in other words the bus line ( backplane bus ) will be broken. so CPU no longer access to all modules. this is an error and will be diagnose by the CPU.so the CPU goes to STOP mode.

I think there is no way to prevent STOP mode of CPU in this case. unless you do not turn OFF the PS.

was Helpful?

Please rate it !

Best regards 

Hello Tekabi,

you're right.

that's what happen. And there's no way to prevent STOP mode of CPU

Thanks

Hello bantonio

Your welcome