Need Help with PLC 5

wdasun

Member
Join Date
Apr 2017
Location
Michchigan
Posts
1
we have a system that's has 6 station which are running on control logix processors and they talk to a PLC 5. at about every 6-7 month 2 or 3 control Logix processors would crash and lose all there programs. any help I can get to figure out what's going on here?
 
I haven't had a control logix PLC crash and lose its program yet, but i have had a few compact logix PLC's do this. Its usually because a sensor, solenoid, or maintenance shorted something out and it erased the PLC program.
 
Welcome to the forum wdasun! In order to help us help you, please consider the following suggestions:

1. Always supply the make/model numbers of the parts in question to help narrow the scope of possibilities. As Mispeld mentioned, firmware info is important with processors especially.
2. Is it the same two/three processors that lose their programs or different ones?
3. Your title states you need help with a PLC5 but your text indicates you need help with ControlLogix. Can you clarify which flavor of processor is failing?
4. Do the failures occur at a certain time (like 4:55pm on Friday) or under similar circumstances (like, whenever we're making recipe XYZ, during a thunderstorm, etc.)
 
Welcome to the forum wdasun! In order to help us help you, please consider the following suggestions:

1. Always supply the make/model numbers of the parts in question to help narrow the scope of possibilities. As Mispeld mentioned, firmware info is important with processors especially.
2. Is it the same two/three processors that lose their programs or different ones?
3. Your title states you need help with a PLC5 but your text indicates you need help with ControlLogix. Can you clarify which flavor of processor is failing?
4. Do the failures occur at a certain time (like 4:55pm on Friday) or under similar circumstances (like, whenever we're making recipe XYZ, during a thunderstorm, etc.)
I would add:

5. A description of the network architecture (if the network is ControlNet, provide also the ControlNet modules firmware version).
6. How do the controllers are powered?
 
I would add that if a Logix5000 series of processor erases its program, it is the result of an "Un-recoverable Major Fault", and is not caused by a programming error.

A bad program, such as an attempt to read/write an element outside of an array due to a bad index, or a Timer is executed that has a negative PREset, or ACCumulator, will cause a "Recoverable Major Fault". If a recoverable major fault is not trapped and reset, then the controller will "Fault", but the program will remain.

Your situation sounds exactly like the symptoms described in the technote linked by Mispeld..., it states:-

"After approximately 3 to 6 months of continuous operation, ControlLogix and FlexLogix controllers at the firmware revisions listed above experience a non-recoverable major fault."

The document also details work-arounds that don't require replacing the processors, or upgrading their firmware to another revision.
 
The firmware version could be very important. For example, version 18 has a known issue where a bit can be written to using PLC/SLC mapping that will wipe out the program and crash the processor.
 
The firmware version could be very important. For example, version 18 has a known issue where a bit can be written to using PLC/SLC mapping that will wipe out the program and crash the processor.

Do you have any detail on that Archie ?

Considering all databases are empty when you start a program, what "bit" can be written to ?
 
Do you have any detail on that Archie ?

Considering all databases are empty when you start a program, what "bit" can be written to ?
In the release notes for version 19, under the corrected anomalies section, it's explained kind of cryptically like this:

"When you use PCCC command bit write (CMD 0F FNC 02) to execute bit-level writes to a controller, the PCCC command appears to complete successfully but does not. Consequently, the data in the controller does not change in the targeted address in the memory. Instead, the write operation writes to the wrong address in memory; this may potentially cause a major non-recoverable fault."

This is basically what it means.... If you use an HMI such as a PanelView with the SLC/PLC driver, then map an integer in the ControlLogix using the PLC mapping, and write to a bit within the integer, it will not work and will very likely corrupt the program in the controller.

I generally try to avoid mentioning these type of things in the public forum because a hacker can use it to make an attack. So I hope anyone who reads this and uses version 18 will take it as advice to upgrade their controllers.
 
I generally try to avoid mentioning these type of things in the public forum because a hacker can use it to make an attack. So I hope anyone who reads this and uses version 18 will take it as advice to upgrade their controllers.

In this case the "hacker" would need to know the mapping, or it would just be trial-and-error trying to find a mapped PLC/SLC style file number - if one existed at all.

But good advice for anyone running V18....
 

Similar Topics

Hi guys, I have no experience when working with AllenBradley PLC, but I hope someone could clarify the result of multiplication shown in the...
Replies
14
Views
2,132
This is the problem, I need to solve it using a ladder diagram: Write a table of inputs and outputs and propose a control solution for a screw...
Replies
22
Views
3,891
I will be designing an automated hydrostatic system. The system on paper works like this, a plc like the click will get information from an hmi...
Replies
227
Views
42,476
I am working on setting up my own 1756 B series PLC rack, power supply 1756-PB75 /B, 1606-XLS480E -redundant 24 DC power supply, controller...
Replies
6
Views
4,279
Hello. I am working on a PLC program that needs to check input 1 after timer two is complete to see if a valve can close or not. Below is the flow...
Replies
9
Views
2,786
Back
Top Bottom