Application site:

CPU416-2 DP, connect with PNPN coupler. Often get information in PLC diagnose information like below:

Event 120 of 120:  Event ID 16# 39B4

I/O access error when updating the process image output incoming

Access error occurred with user data 

Process image partition no.:  0

Start address of I/O area involved:   1000, Length of the area: 196 

Requested OB: Program execution error OB (OB85)

Priority class: 25

External error, Incoming event

11:23:06.918 AM  02/26/2016

(Coding: 16# 39B4  1955  5750  2943  00C4  03E8)

Event 118 of 120:  Event ID 16# 3942

Module problem or maintenance necessary

Module type: Distributed I/0s

Input address: 16372

Channel information available

User information available 

Module/submodule fault

External module error

Channel error detected

Requested OB: Diagnostic interrupt OB (OB82)

Priority class: 25

External error, Incoming event

11:23:06.936 AM  02/26/2016

(Coding: 16# 3942  1952  C554  3FF4  0D33  0000)

Normally, the PN modular can recovery automatically.

Message like below:

Event 117 of 120:  Event ID 16# 3842

Module OK

Module type: Distributed I/0s

Input address: 16372

Channel information available

Requested OB: Diagnostic interrupt OB (OB82)

Priority class: 25

External error, Outgoing event

11:25:21.197 AM  02/26/2016

(Coding: 16# 3842  1952  C554  3FF4  0013  0000)

But today, this error cause CPU stop.

Event 25 of 120:  Event ID 16# 494D

STOP due to IO error 

No relevance for user (Z1): 9182

No relevance for user (Z2): 03b0 (Z3): 04f9 

Previous operating mode: RUN 

Requested operating mode: STOP (internal)

External error, Incoming event

Currently, find one abnormal condition is that the two power supply to this PNPN coupler, only switch on one. So turn both power source. Then keep monitor.  

If some one also met this problem in project.  Please give your suggestion.

Thank you in advance.

Xiaoxiao2015

Event 120 of 120:  Event ID 16# 39B4

Requested OB: Program execution error OB (OB85)

Event 118 of 120:  Event ID 16# 3942

Requested OB: Diagnostic interrupt OB (OB82)

Event 117 of 120:  Event ID 16# 3842

Requested OB: Diagnostic interrupt OB (OB82)

 As highlighted by CPU Diagnostics, you should download OB82, OB85 in PLC.

These 2 will keep your PLC in runtime.

Simply add New organization block > Name it to OB82

add New organization block > Name it to OB85

and download these two.

Thanks for your suggestion. In the project, it already had block OB82 and OB85.

Xiaoxiao

Event 25 of 120:  Event ID 16# 494D

STOP due to IO error 

No relevance for user (Z1): 9182

No relevance for user (Z2): 03b0 (Z3): 04f9 

Previous operating mode: RUN 

Requested operating mode: STOP (internal)

External error, Incoming event

 hi Xiaoxiao,

see the other Threads about this error in this forum:

Event ID 16# 494D STOP caused by I/O error

CPU goes to Stop with I/O error on diagnostic buffer

like you can see in the existing discussions, it would be easier to contact Siemens directly. 

Start a Support Request.

hope this helps,

regards,

Hi all,

Thanks for your information.

After check site condition, find the two power supply to PNPN coupler only one is switch on.

The error not happen again until now. 

For problem happened in this project, Could be the possibility that only one power supply to PNPN coupler, can cause PNPN coupler not work stable. 

Hope this information can help other engineer. And it also remind me to check PNPN coupler power supple in future project..

Xiaoxiao2015

...

For problem happened in this project, Could be the possibility that only one power supply to PNPN coupler, can cause PNPN coupler not work stable. 

...

I don't think so.

The DP/DP coupler has a switch to adjust, that both power supplys are valid.

So, If one power is lost, the coupler will still work.

It will be the same thing with PN/PN coupler, please check the DIP switches...

I Think you need to Activate "Report System Error"  and download the program again after generating the OB's for Reporting system error.

In report system errors you will also get to decide on what condition your CPU should go to STOP.