s7-300 CPU error problem

dwivedi · Dec 28, 2007

Dear All,

we are having a siemens make plc S7-315-2DP, the plc is showing the following errors :-

SF fault - LED red colour
Stop LED - amber colour
run LED - green colour ( Blinking )

on going online the messages that we are in the diagnostics is attached with this thread.kindly refer to the same.We would like to know if the CPU is faulty or its some other fault present.

manmeetvirdi · Dec 28, 2007

Hi there
Place the OBs like OB80,82,85,86,87,121,122
in your program(Libraries-->stdlibs-->stdobs)
and load them into CPU.

OK Green light blinking!!!
Green light will be either OFF or ON, and as far as I know blinking only happens when you place the CPU in run mode!

Also have you compiled your Hardware configuration? Is it error free?

prasadtoke · Dec 28, 2007

the PLC was running for around 3 years and sudenly this problem arised so i don't think it is anytihng to do with the hardware config.Anyways thanks for the help iwill install these OBs ar you sure its not a hardware problem as STOP and RUN LEDs are on at the same time.Run is blinking green

manmeetvirdi · Dec 28, 2007

hmmmmmmmmmmmmmmmm
OK try to simulate your program in PLCSIM
If everything is OK over there then its a problem with your hardware.
Seems that modules in slot 5 and 6 are giving the problem.
Also make your hardware configuration ONLINE, and see if there are any cross marks,which in turn indicates the faulty module.

prasadtoke · Dec 28, 2007

all modules except the CPU and the IM 365 have red strokes over their symbol in the online diagnostics.i will check with PLCSIM but i don't have the software right away can u tell me anything else to be sure of the exact nature of the prolem

JesperMP · Dec 28, 2007

It looks like a hardware error, so forget about PLCSIM in the first place.
The CPU cannot "see" the modules in slot 5 and 6, and there are other errors that may or may not be related to the same i/o modules.

Try to remove and reinstall all modules. This only to give the contacts in the backplane a "massage".

Try to swap identical modules, and see if the error disappears or follows one of the i/o modules.

Try to exchange the modules with factory fresh ones. In particular the modules in slots 5 and 6.

prasadtoke · Dec 28, 2007

the orignal configuration is in the following order:

IN the main rack PS307,315-2DP,IM365 Send,Dummy module DM370,4channelAO in slot5,4channelAO in slot 6, 8 AI in slot7, 32DIin slot 8,32DI in slot9,32DI in slot10,32 DO in slot 11

in subrack IM365 receive in slot 12,32do in slot 13 ,32do in slot 14

we tried to make a completely new configuration with only the CPU and the modules in slot 5&6 and found out they are working just fine.
but as soon as we download the orignal configuration with its program and connect the entire hardware as it was connected orignally we get SF and Run blinking and STOP led on the CPU.
what should we check now?

JesperMP · Dec 28, 2007

Remove the dummy module and download a modified HW config, see if the error disappears.

You can also relatively easily swap the IM send and recieve modules, and move the CPU to the IM send modules new position.
Then download a modified HW config and see if the error has gone. If there is now errors on the new modules connected to the right side of the IM send module, then you know that the IM send module is defective.

manmeetvirdi · Dec 29, 2007

A good diagnosis prasadtoke

Ok your CPU is good
your AO modules are good and working.

But when you connect them back with orignal configuration then same problem comes up, so surely there is problem in between the Ao modules and CPU.This is further supported by the fact that you are getting cross mark in both CPU and that IM module.
So try exchanging this IM module with those in other rack or freash one.
And replace both 40 pin connectors which connect IM with CPU and Ao module.

PeterMalt · Dec 29, 2007

Maybe replace module in slot 4

dwivedi · Dec 29, 2007

we have changed the position of the CPU, installed at the position of IM module, and hard ware configuration done accordingly with out using its second rack and found there is no fault on the CPU, but say if there is any fault on the DO modules connected after the IM module in the second rack, how can we confirm that there is fault in the IM module or in the DO module.

manmeetvirdi · Dec 29, 2007

Put DOs in first rack and see

s7-300 CPU error problem

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