CPU412-2 stop due to External error and BUS2F

We have facing one issue from 1 month ago. 1 system packing machine connect via profibus among Filling - Buffer-Conveyor with Conveyor as Master. During running production, CPU S7-412-2 of Conveyor Stop and Led EXTF lit, BUS2F flashing. Then we normally OFF power and ON again, the issue gone. But it happens again 2-3 days later. We also replace new CPU but not solved.

And one special day, 28/12/2022, issue happens but we cannot reset by OFF and ON power. After that we did something like swap module ..still not work. Then we download a backup PLC program and then it work.

After that few days, 6/Jan/23 it happened again and we changed 3 new modules DI, DO, AO. But it still happened yesterday, then we swap these 3 modules because we only have 3 new modules.

Question:

1. How can we know where the problem come from?
2. If we have problem with IO module, but I know that modules have not diagnosis feature?
3. If the problem with profibus, why CPU stop?
4. Or problem with Firmware of CPU hardware and software

 Hello,

Nguyen Phi Long

We have facing one issue from 1 month ago. 1 system packing machine connect via profibus among Filling - Buffer-Conveyor with Conveyor as Master. During running production, CPU S7-412-2 of Conveyor Stop and Led EXTF lit, BUS2F flashing. Then we normally OFF power and ON again, the issue gone. But it happens again 2-3 days later. We also replace new CPU but not solved.

And one special day, 28/12/2022, issue happens but we cannot reset by OFF and ON power. After that we did something like swap module ..still not work. Then we download a backup PLC program and then it work.

After that few days, 6/Jan/23 it happened again and we changed 3 new modules DI, DO, AO. But it still happened yesterday, then we swap these 3 modules because we only have 3 new modules.

Question:

1. How can we know where the problem come from?
2. If we have problem with IO module, but I know that modules have not diagnosis feature?
3. If the problem with profibus, why CPU stop?
4. Or problem with Firmware of CPU hardware and software

1. CPU diagnostic buffer generally. In case BF it is some DP part not accessible, power not ON, error on other Master DP network, ... From your HW cfg is clear you cooperate with other independed PB networks because of DP couplers probably. Problem can be also write wrong or not actually accessible parts of memory, here diagnostic buffer can help. I recommend to have correct date and time set on all CPUs at your network to have good data for diagnostic.

2. pls describe better.

3. no diagnostic OBs downloaded probably. In your case maybe better because then you know you have problems. In case of OBs you have, CPU doesnt STOP, ERR LEDs are ON but you need do in your code correct possible error handling/diagnostic from process, as mandatory.

4. hard to say.

Duris_I

 Hello,

Nguyen Phi Long

We have facing one issue from 1 month ago. 1 system packing machine connect via profibus among Filling - Buffer-Conveyor with Conveyor as Master. During running production, CPU S7-412-2 of Conveyor Stop and Led EXTF lit, BUS2F flashing. Then we normally OFF power and ON again, the issue gone. But it happens again 2-3 days later. We also replace new CPU but not solved.

And one special day, 28/12/2022, issue happens but we cannot reset by OFF and ON power. After that we did something like swap module ..still not work. Then we download a backup PLC program and then it work.

After that few days, 6/Jan/23 it happened again and we changed 3 new modules DI, DO, AO. But it still happened yesterday, then we swap these 3 modules because we only have 3 new modules.

Question:

1. How can we know where the problem come from?
2. If we have problem with IO module, but I know that modules have not diagnosis feature?
3. If the problem with profibus, why CPU stop?
4. Or problem with Firmware of CPU hardware and software

1. CPU diagnostic buffer generally. In case BF it is some DP part not accessible, power not ON, error on other Master DP network, ... From your HW cfg is clear you cooperate with other independed PB networks because of DP couplers probably. Problem can be also write wrong or not actually accessible parts of memory, here diagnostic buffer can help. I recommend to have correct date and time set on all CPUs at your network to have good data for diagnostic.

2. pls describe better.

3. no diagnostic OBs downloaded probably. In your case maybe better because then you know you have problems. In case of OBs you have, CPU doesnt STOP, ERR LEDs are ON but you need do in your code correct possible error handling/diagnostic from process, as mandatory.

4. hard to say.

 Thank Duris

1. Please take a look with diagnostic buffer as attached file for more detail 

2. In case one of modules have problem, but itself can not show error signal as LED. So we can not detect which one 

3. There are some necessary OB (1,35,82,85,86,100,122) in my program. How do I know which one missing? 

Hello,

and you have take a look at this diagnostic buffer? For example, what about Event n.12? You can read event by event and read description, compare with HW cfg and do some steps.

Looks like your problems you have quite long time as is clear from diag buffer 

Yes. I did but not good at this. 

I just study and find that maybe the problem still come from Distributed I/Os because LED BUS2F blinking, and CPU stop due to OB86 not programed. Ah But I did not see any requested OB 86

If so, I should take into account Profibus connection health check. But it is difficult to find out it which belong to Profibus.

Hello,

maybe OB87 and OB121 I expect to have inside CPU, for sure. Look, you have attached one screenshot where only PB and DP Couplers are vissible so hard to think about any other networks and also types.