Modbus TCP will stop responding to master but can ping

[AAsher]

Using a V130 configured for TCP I am using an external device to continuously poll the state of a blocks of registers.

This works fine for several days but occasionally will simply stop responding to modbus requests. I can ping the V130 and connect to it using Visilog so I know the IP address is setup correctly but no modbus activity is possible. Once I reboot the V130 everything works until it stops responding again after a few days.

Any suggestions on what I should look for would be much appreciated.

These are the TCP setup rungs

[Gabriel Franco]

If you post your code, I can take a look.

 

So far, make sure SB168 is set at power-up

[AAsher]

36 minutes ago, Gabriel Franco said:

If you post your code, I can take a look.

 

So far, make sure SB168 is set at power-up

Thanks Gabriel! I will set SB168 and watch what happens. It's intermittent but I should know in a few days if that solves the issue.

[Fernando Castro]

I had a similar problem with one v700 ( just 1 from 100), never found the issue I added an internal reconnection function in the ladder logic monitoring if the socket status has no connection for like 3 minutes. But still haven't ran the PLC long enough to see if that solved the problem

[Ausman]

@Cara Bereck Levy I must be missing a perfectly valid reason why SB168 doesn't default as set at power-up.   We often have users not knowing about this, and it seems a bit odd to me that it has to be activated when it is actually an essential part of the process.

cheers, Aus

[Flex727]

I've always wondered this too. I suspect the creators had something in mind that was a problem if it was set when it didn't need to be.

[kratmel]

6 minutes ago, Flex727 said:

I suspect the creators had something in mind that was a problem if it was set when it didn't need to be.

This is not related to this topic, but in an empty project for some reason 0 is written in SI285 and I could not understand why this is done. Look at the STL view of the empty ladder program...

[Fernando Castro]

2 hours ago, Ausman said:

@Cara Bereck Levy I must be missing a perfectly valid reason why SB168 doesn't default as set at power-up.   We often have users not knowing about this, and it seems a bit odd to me that it has to be activated when it is actually an essential part of the process.

cheers, Aus

SB 168 should be turned ON at power-up. It is OFF by default to preserve backwards compatibility with applications created previous to OS 4.70 B14. If SB 168 is ON, when the Ethernet link fails, the OS saves the Ethernet parameters and resets:    • SB 142 Card Initialized    • SBs 143-146 Socket initialized (Sockets 0-3)    • SBs 147-150 Socket connected (Sockets 0-3) When the Ethernet link is reestablished, the O/S performs CARD INIT and SOCKET INIT for all 4 sockets according to the saved parameters.

 

Speaking of that, this is one of those bits that does not work for v700 right? 

[Ausman]

Thanks Fernando, it's been so long since I first discovered this that I'd forgotten that part.  Isn't it amazing what one finds when you look up Help!

I don't know the answer re V700s.

cheers, Aus

[Flex727]

11 hours ago, Fernando Castro said:

Speaking of that, this is one of those bits that does not work for v700 right? 

I don't know the answer either, but I just checked and you do not get the compile warning on a V700 like you do with the other models.

[Fernando Castro]

13 minutes ago, Flex727 said:

I don't know the answer either, but I just checked and you do not get the compile warning on a V700 like you do with the other models.

I just tested on v700  that bit is 0 on v700 even if you set the power up value to 1 and can not be set to 1 so the answer is that It is not compatible with v700