v700 sudden power loss, the PLC doesn't reconnect

[Vipavko]

Hi everyone,

I'm experiencing an issue with V700 PLC that I hope someone here can help with. Whenever there's a sudden power loss, the PLC doesn't reconnect or resume operation once the power is restored. This problem is causing significant downtime and disruption to our processes.

Here are the details:

• Model: V700 PLC
• Issue: Fails to reconnect after sudden power loss
• Symptoms: After the power is restored, the PLC remains offline and doesn't resume normal operation. A manual restart is required to get it back online.
• Additional Information: When I manually restart the PLC, it reconnects immediately and operates normally until the next sudden power loss.
• Attempts to Fix: I've checked the power supply connections, ensured the firmware is up to date, and reviewed the PLC's settings, but nothing seems to resolve the issue.

Has anyone else encountered a similar problem? If so, what steps did you take to fix it? Any advice or troubleshooting tips would be greatly appreciated!

Thanks in advance for your help.

[kratmel]

Try to replace power supply to new another one from other brand.

If IO present (SNAP or EX-A2X Expansion Adapter) - IO must be powered from the same power line.

[Ausman]

7 hours ago, Vipavko said:

the PLC remains offline

As well as Kratmel's suggestions, when you  say "offline", what exactly are you meaning?  Wondering if you mean it has dropped the ethernet connection?  If so, try setting SB168 to be a power up value of 1.

cheers, Aus

[Vipavko]

18 hours ago, Ausman said:

Wondering if you mean it has dropped the ethernet connection?  If so, try setting SB168 to be a power up value of 1.

 

Yes, dropped conncetion with remote computer !  

Where can i do that ?  (  try setting SB168 to be a power up value of 1) 

[Ausman]

1 & 2 are mainly assuming SB168 is OFF.  If it is already ON, which you'll find out during doing the following,  then something else is astray.  A "sudden" power loss might mean a very brief interruption, which can play havoc with some settings.

1). You would normally use Visilogic to see if it has a power up value of 1.  SB168 is listed in System Bits.  In any new project it defaults to being off, and you have to change it to a 1 in the power up value for the automatic recovery to occur.  No other alterations needed to your program.  Compile the program, save as a new name, then send it to the controller using whichever Download option you want to use.

2).  If you don't have the program so that you can open it in Visilogic, you can manually get to SB 168 by using Info mode.  Once you have got into Info mode, follow the screen messages to work your way through to SB168 and see whether it is on or off.  Thinking on this a little more as I write, I suggest you actually do this in the first place.  It will easily show whether the program is setting it on or not.  If it's off, turn it on and see what happens with the connection.  I'm not sure whether the ON setting is retained after a power cycle if the bit is set via this means......I've always set it in the program.  It may hold onto it during a power cycle, but I don't think so.  I simply don't know for sure and can't test it at present....

Either way, if it's off, change it to 1, run things and see if the connection is retained.  If it's on, then I'd be looking at things in your control cabinet like Kratmel has spoken of, and also the possibility that power loss is causing large spikes that upset the ethernet system.  Unclamped contactors and coils etc all shutting off at the same time will create problems, and not only for ethernet but the plc itself. 

cheers, Aus

[Flex727]

2 hours ago, Ausman said:

It may hold onto it during a power cycle, but I don't think so.  I simply don't know for sure and can't test it at present....

I don't have time to test this either, but I can't imagine that this would be the only bit value that isn't retained during a power cycle (with battery).

[Vipavko]

 

hm,there is no SB168......

[Flex727]

7 hours ago, Vipavko said:

hm,there is no SB168......

You're not going to "Find" it if you're not using it in your project. Just go to Operands, scroll to System Bits, then scroll to 168. There you can set the Power-Up to "Set".

[Ausman]

[Ausman]

Also, you've said the "firmware is up to date".  Does this mean you have updated the firmware to the very latest version done via 9.9.00?  If so, you need to update your program using the same version.    New security features were implemented and some odd things can occur without the two working together properly.  For detailed instructions on this, open the Click Here displayed in the forum home page under News and Announcements.

More specific questions.... what version of Visilogic was used to give the screenshot you provided?  Is the system connected to the outside world?

[Vipavko]

thank you Flex727 and Ausman, i find it  and It is active "1"

 

 

[Vipavko]

but the main problem is still there !

[Flex727]

On 7/3/2024 at 12:48 AM, Vipavko said:

When I manually restart the PLC, it reconnects immediately and operates normally until the next sudden power loss.

What do you mean "manually restart"?

[sgull]

You say that when you get a power loss you lose connection with a remote computer.

when you cycle the power on the PLC the connection comes good again.

when you say you get a power loss, do you lose the power to the PLC and the remote computer?

If so then the PLC may be starting up before the remote computer on a power fail.

if the PLC tries to communicate and the computer is not ready it may time out.

it should be possible to put a delay after the PLC power up before communication starts in order to give the remote computer time to boot.

you may need to describe your complete setup more if this is not the issue.

[Vipavko]

I tested, I turn off power only on PLC, and problem is the same

[Flex727]

9 minutes ago, Vipavko said:

I tested, I turn off power only on PLC, and problem is the same

How is that different than "manually restart"?

[DanT]

Hi;

Post  image(s)  of the Nets with Power up   SB2  in them.

Curious about the sequence  of  the   power up  operation.

Are any of these   Power Up  SB2's in subroutines?    when are they called?

DanT

 

[Vipavko]

1 hour ago, Flex727 said:

How is that different than "manually restart"?

Power is turn off ( not with a button, but UPS and eletrical switch is turn off, simulation of sudden power loss )

[Flex727]

11 minutes ago, Vipavko said:

not with a button,

What button? Details matter when troubleshooting a problem. You need to fully describe what you're doing and it would also be very helpful if you would post your program, or at least the portion where communications are initiated on start up (as DanT suggested).

[kratmel]

On 7/3/2024 at 8:48 AM, Vipavko said:

Has anyone else encountered a similar problem?

I found the similar problem in other PLC hardware. Please try to use my sample code  for second restart PLC.  If second restart help with issue - your PLC has hardware problem and must be replaced.

 

[Ausman]

There is FAR more information needed here than first given.  

9 hours ago, Vipavko said:

but UPS and eletrical switch is turn off, simulation of sudden power loss

What does the UPS power?  What does the elec switch control?  How long does the UPS run whatever it is connected to on a power failure?  If power fails and the machinery being controlled goes off immediately,  yet other control gear stays on due to the UPS, who knows what's going to happen.  DanT has noted "correct sequence of operations" and the more you describe the situation,  the more this becomes the culprit.

All of this info should have been included in your first post.