Fail Safe

Hi
I am working on Siemens Fail safe CPU.
when i download the program, Cpu Stops by the result of F_TESTC FB.
In Diag. buffer it tells that cause of stop is F_TestC.
Can anybody help me how i can know what is main reason?

Regards
Hooman

hooman said:

Hi
Cpu Stops by the result of F_TESTC FB.

Click to expand...

Is this FB (Function Block) present in the CPU?

I am assuming that this FB is being called in the program, but it doesn't exist in the PLC.

Can you post exactly what the diagnostics buffer states, or maybe post a screen shot.

Paul

Here's what the help says: (this can be found by clicking on help on event from the diagnostic buffer display)

Safety Program: Error detected in F_TESTC

Explanation:
The F-FB F_TESTC is used to check whether the background self-tests for the F-CPU were performed fully and without error. If an error is detected, F_ TESTC either shuts down the F-runtime group within the OX3x or the entire Safety Program (fully or selectively, depending on the parameters of the FULL_SD input in the F_SHUTDN FB).
This event contains the instance DB number in F-FB F_ TEST that detected the error.


Possible Causes of Error:

Error in one of the F-CPU background self-tests
Illegal online manipulation of the Safety Program.
Internal RAM or F-CPU failure

To Correct the Error:

1. Check whether the background self-tests in the F-CPU were shut off by SFC90 H_CTRL. These tests must not be shut off.

2. Check that the F-CPU text-cycle time was set at < 12 hours in the CPU "H Parameter" properties.

or

· Restart the shut-off logic.

· Shut off the CPU and perform a cold restart.

· Perform a complete download of the user program to the CPU.

· Replace the CPU.

Dear Simon
Thank you very much for your Reply.
This is second Event of my Diag. Buffer.
****************************************************************
Event 2 of 120: Event ID 16# 457F
STOP caused by STOP command
Breakpoint in user program: Cyclic interrupt OB (OB 35)
Priority class: 12
FB number: 399
Module address: 1712
Previous operating mode: RUN
Requested operating mode: STOP (internal)
Event occurred in the master CPU in rack 0
Internal error, Incoming event
03:02:22:380 pm 08/04/94
***************************************************************

Best Regards
Hooman Jahanbani

Sorry, I don't have any experience with fail safe CPU's - I was just pointing you to the help that is available from within Step 7.