siemens S5, 115U CPU 942

newbee

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Join Date
Jul 2007
Location
winchester,va
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Hello again, i have a old siemens S5 processor that stays in the stop mode. i have tried to place the run/stop switch from run to stop and the run again, power down(to no use). the CPU does have an e-prom. my question is if i do an overall reset will i lose anything? the processor doesn't have a backup battery and every night the power is turned off and turned back on in the morning when work resumes.(just not this time). does anyone know the switch sequence to preform an overall reset or know off another way to try and get the processor back in the run mode,🤞🏻
 
There are 2 types of resets

If you have 2 switches, 2 position run/stop and 3 position NR/RE/OR

For a normal reset put the switch in the nr position take the other switch and put in from run to stop to run, this will reset the CPU

If you hold the switch in the OR position and move the other switch from the run/stop/run this will clear the CPU memory....

If you are wrong about your eprom then *** you can and will loose your program *** make sure you have a current copy of your program you will need to reload it

I think this will work on yours, good luck
 
I have never had a issue with it, but... that not to say you will not

If you power down every night and you don't have a battery, then I don't think you will have a issue, your program is on your eprom

Some CPU's are half and half (lack of better words) some of the program is on the eprom then others store it all, I dont think yours stores anything on the CPU as you turn off your power (with no battery)

Do you have a way of hooking up to the PLC and reading the program?

I think I would try it, but thats me, worse case it won't work and you are no better off then you are now

Make sure you come back and post again, let us know
 
The Eprom will acrry all the program.

On initially starting it will transfer the dynamic data (Data Blocks) into normal memory.
 
newbee said:
Hello again, i have a old siemens S5 processor that stays in the stop mode. i have tried to place the run/stop switch from run to stop and the run again, power down(to no use). the CPU does have an e-prom. my question is if i do an overall reset will i lose anything? the processor doesn't have a backup battery and every night the power is turned off and turned back on in the morning when work resumes.(just not this time). does anyone know the switch sequence to preform an overall reset or know off another way to try and get the processor back in the run mode,🤞🏻
Click to expand...

Is the Amber Battery LED on, indicating a dead battery?
Are you able to go online to check the ISTACK to see what is making the CPU crash?

Ian
 
there is no battery in the CPU it has a e-prom. i have no way of going online with the processor, another question if i do an overall reset does that just erase the program and rest the processor? it will not harm the e-prom will it? and after the overall reset then you just down load the e-prom to the processor>?
 
An overall reset will not clear the EPROM.

If it makes you feel better, switch off power and pull the EPROM, power up and do an overall reset (it should be clear then in any case as there's no battery), then kill the power again and re-insert the EPROM.

On power up, only the original program in the EPROM will remain.


If it is an E-Prom, you would need ultra violet light to clea it.

If ot is an EEPROM, then you would need a program to command a reset.
 
Also as informed above, if the program is going into STOP, the ISTACK should tell you why.

If the program is on EPROM and there has never been a battery, so powering down regular means the EPROM program should be OK.

It is likely to be a hardware problem.

If the EPROM has suffered some fault and is corrupt, you are buggered in aby case, unless you have the software as back-up.
 
ok, all is well. we did an overall reset and everything seems ok. but when we disconnect the main power and apply power again the CPU remains in the stop mode(will reset after an overall reset) the siemens tech told us to try and install battery and see if that helps. i am also pricing a replacement CPU as an option.

thanks for all the help everyone has offered.
 
newbee said:
... i am also pricing a replacement CPU as an option..
Click to expand...

Don't go back with a S5, upgrade to a S7, How many I/O's do you have? any analog?

newbee said:
... thanks for all the help everyone has offered.
Click to expand...

Thanks for coming back and updating us, its nice to see when the advice works and problems are solved
 

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