Siemens Step 7 CPU 315F-2PN/DP Not possible to go Online anyway and anymore

[racartapo]

Hello,

I really need help to understand what happened in a few machines that use Simatic Step 7 315F-2PN/DP CPU's.

Without any reason I can't go any Online anymore, it is a complete production line, but these 2 machines are not possible to access online.

These PLC's are connected to other machines via Ethernet, also each one has a Profibus network to manage all the VFD's.

Everything runs properly, all communications with all machines are working correctly but I can't connect online anymore.

I used to connect almost every day but for 2 days ago it is not possible.

I tried via Ethernet as usually, I tried via Profibus using an USB interface to Profibus CP, I tried everything but not possible.

I can ping the plc to the ip address and this respond properly but I can't connect online anymore.

I got a message that says: Monitor (33:16662) Online: the connection to the target module cannot be stablished.

I tried to create a new project to pull all files using Upload Station to PG but this doesn't see the IP address neither see the PLC in Profibus.

I didn't reset the PLC memory using MRES because this has a password for the safety part, and I don't know the password. If I lost something I will be in trouble for sure.

If somebody can give a light or idea why these two machines are not possible to access online, the rest of machine using Siemens PLC's I can access no problem.

I never seen a situation like this before.

Thanks in advance for your help

Racartapo

[sania]

do you can connect to any another plc over tcp?
try disable firewall
have ping to cpu?
are you try connect over it network or directly?
offtop : windows make update few days ago...

with connection over pb are you change "set pg/pc"?
try "assembly nodes" to check witch station exist.

[racartapo]

Hello Sania, thanks for your answer.

I am answering here:

do you can connect to any another plc over tcp?
- Yes, I can connect to any other PLC, they are Siemens and it is not any problem[/b]
try disable firewall
- I wil try but if the other PLC's respond, I dont see that will help
have ping to cpu?
- Yes, I can ping the CPU and this respond as the others but no possible to go online any more using Step 7
are you try connecting over it network or directly?
- I tried both, over the network and using interface for Profibus but nothing works.
- When I use Profibus, I am able to see all Profibus devices, but the CPU is showing as device "000" not as CPU as usual.
offtop : windows make update few days ago...

with connection over pb are you change "set pg/pc"?
- Yes, I tried using different interfaces over Set PG/PC but nothing works, like I said all others PLC's at the same network, no problem.
try "assembly nodes" to check witch station exist.
- Ok I will try

Honestly, I never seen something like that, the issue is coming from the PLC in these two machines, for some reason is not allowed to stablish online connection

[sania]

are you in same subnet?
are you sure unique ip of cpus and pc in network?
are your cpu have gateway/router settings? and your pc?
are you have upload? share print screens with ip settings

[Dfcz]

There was a similar case. Suddenly, two processors stopped seeing each other on the network. Without details and briefly: after two days of searching and boiling brains, it turned out that before that the service on duty changed the segment of the network cable.

Был похожий случай. Вдруг два процессора перестали видеться в сети. Без подробностей и коротко: после двух дней поиска и закипания мозгов, оказалось, что перед этим дежурный сервис менял сегмент сетевого кабеля.

[racartapo]

Hello,
sorry for the delay in my answer but we still fighting with these PLC's

So, we still not able to connect online to this PLC.
Now we found that if we disconnect the Ethernet cable from the network, then it is possible to connect online using Profibus or even via Ethernet if I connect a cable directly to the PLC Port.
We asked network administrator to check all about it and they said that all looks good since machine still running in production communicating with the others plc's via Ethernet.
Very weird problem because still communicating with others plc's, all work well but not possible to access online neither Ethernet or Profibus when this is connected to the network.
If machine is connected to the network, when I try to access online via Profibus, the Windows that shows Accesible Nodes, this shows ID 2 as "0000" instead of showing as 315CPU as usually.
It shows the rest of Profibus devices properly as IM151 or Danfoss, etc.. but CPU this shows as 0000.
We asked Network administrator to check all settings around but they said everything looks good, since machine still running in production communicating with the other machines properly.
I got some pictures to show but I dont know how to include them here.
Any idea, please?

[sania]

upload your project
witch mpi address of tcp card?

[racartapo]

Hey,

Just to let you know I finally got it, I can connect online now.

What I did was that I disconnected the Ethernet cable from the network and I connect to the PLC via Profibus directly to the port.

In this way I was able to connect online and check the amount of PG allowing for communication under PLC settings.

The original settings for PG is = 2, if we disconnect the Network cable we can see that only 1 PG is connected, the one that is via Profibus.

Then, as soon as we connect the Network cable, then this PG shows that there are 2 PG connected, which doesn’t make sense.

Anyway, to make a test, we increased the amount of PG’s connected allowed to the PLC from 2 to 4, then we connected back the Network cable.

Now the PLC shows that PG’s connected to the PLC are 4, which is even more crazy. The good news is that after we increased the amount allowed to 4, now we are able to connect online, it is working good.

But now, this shows that 5 units are connected and it is only 1 which is my computer when I go online.

We believe that the network in some way is telling or setting the PG as full and that was why this was not able to connect.

Any other machines are set PG = 2 and it is working.

Like I said after changing from 2 to 4 the PG allowed, now I can connect back online as normal as was before.

Thanks a lot for your support and I just wanted to make sure you guys are aware about the solution if somebody else has some issue like that.

Thanks