I’m encountering an intermittent issue where the CPU on my machine is being forced into STOP mode.

The problem appears to be linked to the safety section of the code; however, after a thorough review, I haven’t been able to identify any faults. The machine operates continuously (24/7) and has forced the CPU into STOP approximately 7–8 times over the past week, indicating that the fault is indeed intermittent.

I’ve attached the error messages for reference.

Any guidance or support would be greatly appreciated.

Did you press F1 for TIA Portal's HELP, then search for "Event OD" and then scroll to find 75D6?

It offers quite a bit of information.

I suggest starting there, and insert some logic to latch impossible (in your mind) states that are stated to cause a Safety STOP so you can capture the real problem the very next time it happens.  Then you can insert logic to protect against calculations that result in an invalid safety solution.

For example, in regular PLC logic, anytime you divide, always check if the denominator is ZERO first.  If it is 0, assert an appropriate value for the entire calculation and perhaps even generate an alarm or fault condition, or perhaps simply ignore it for up to a specified amount of time.

We cannot obviously ignore invalid values inside a safety block.  We have to properly address them before attempting to use them in calculations.

Sometimes choosing a tag's datatype without complete understanding is the source of a problem.  Choosing Byte or SInt or USInt might feel all the same in regular PLC logic, but in a safety block, I assume you know why one datatype over another could cause an unexpected overflow for a simple calculation on a randomly noisy analog input channel.

JackRBaker31

I’m encountering an intermittent issue where the CPU on my machine is being forced into STOP mode.

The problem appears to be linked to the safety section of the code; however, after a thorough review, I haven’t been able to identify any faults. The machine operates continuously (24/7) and has forced the CPU into STOP approximately 7–8 times over the past week, indicating that the fault is indeed intermittent.

I’ve attached the error messages for reference.

Any guidance or support would be greatly appreciated.

0_Einstein

Did you press F1 for TIA Portal's HELP, then search for "Event OD" and then scroll to find 75D6?

It offers quite a bit of information.

I suggest starting there, and insert some logic to latch impossible (in your mind) states that are stated to cause a Safety STOP so you can capture the real problem the very next time it happens.  Then you can insert logic to protect against calculations that result in an invalid safety solution.

For example, in regular PLC logic, anytime you divide, always check if the denominator is ZERO first.  If it is 0, assert an appropriate value for the entire calculation and perhaps even generate an alarm or fault condition, or perhaps simply ignore it for up to a specified amount of time.

We cannot obviously ignore invalid values inside a safety block.  We have to properly address them before attempting to use them in calculations.

Sometimes choosing a tag's datatype without complete understanding is the source of a problem.  Choosing Byte or SInt or USInt might feel all the same in regular PLC logic, but in a safety block, I assume you know why one datatype over another could cause an unexpected overflow for a simple calculation on a randomly noisy analog input channel.

JackRBaker31

I’m encountering an intermittent issue where the CPU on my machine is being forced into STOP mode.

The problem appears to be linked to the safety section of the code; however, after a thorough review, I haven’t been able to identify any faults. The machine operates continuously (24/7) and has forced the CPU into STOP approximately 7–8 times over the past week, indicating that the fault is indeed intermittent.

I’ve attached the error messages for reference.

Any guidance or support would be greatly appreciated.

 

Afternoon,

Firstly, Thank you for your response.

I have looked deeper into this issue and still cannot find anything obvious.

In my Main_Safetey_RTG1 FB there is no division blocks or anything other than the following:

ACK_GL x1

TON x6

ESTOP1 x13

Based on the error diagnosis page, it states:

Error: Safety program: Data corruption prior to sending to F-I/O

F-runtime group 1

Start address of the F-I/O: 42

Offset of the output: 0

Therefore am I correct in saying that the error is to do with Q42.0 (This is my first safety output)

I have 8 outputs in total ranging from Q42.0 - Q42.7.

I have attached a screen grab of the network containing Q42.0 for reference.

Any assistance would be really appreciated.

I would look at the HMI DB that you are using in your code. If the HMI writes to that bit during processing of the safety program, then you can get a corruption error…

copy the reset command from the HMI to another DB or bit in your regular program and use that second bit in your safety program