机床偶发出现 810004 报警，几天出一次，关机开机后又能正常使用。

多次去客户现场也没看到故障现象，根据以往经验可能由于 profibus DP 站点掉站引起，就给客户换了接口模块及相关的输入输出模块，还有接头，之后还有偶发故障。

进一步了解情况，了解到客户一般 8 点半上班时开机，17 点下班时关机。建议客户晚上不关机看等待故障出现，出现时也别消除，等现场查看。

故障出现时去客户现场对 CPU 诊断信息进行梳理并做好备份。发现最近几次的故障都是STOP caused by program sequence error，User interface (OB or FRB) not found，而且有个规律都是 11:05 触发报警，这个时间是意大利时间，本地时间是 17:05。

Event 1 of 112:  Event ID 16# 456D

STOP caused by program sequence error (OB not loaded or not possible, or no FRB)

FB number:     15

Module address:      2

Previous operating mode: RUN

Requested operating mode: STOP (internal)

Internal error, Incoming event

11:05:00.002 AM  02/02/2021

(Coding: 16# 456D  FF84  8E00  0101  000F  0002)

 Event 2 of 112:  Event ID 16# 35A1

User interface (OB or FRB) not found

No relevance for user (Z1): 1001

Cause: Time-of-day interrupt comparator 1

OB number: Time-of-day interrupt OB (OB  10)

Priority class:    2

Current OB no. and priority class:

Requested OB: Program execution error OB (OB85)

Priority class: 26

Internal error, Incoming event

11:05:00.000 AM  02/02/2021

(Coding: 16# 35A1  1A55  C350  1001  1111  020A)

 Event 16 of 112:  Event ID 16# 456D

STOP caused by program sequence error (OB not loaded or not possible, or no FRB)

FB number:     15

Module address:      2

Previous operating mode: RUN

Requested operating mode: STOP (internal)

Internal error, Incoming event

11:05:00.003 AM  01/27/2021

(Coding: 16# 456D  FF84  8E00  0101  000F  0002)

 Event 17 of 112:  Event ID 16# 35A1

User interface (OB or FRB) not found

No relevance for user (Z1): 1001

Cause: Time-of-day interrupt comparator 1

OB number: Time-of-day interrupt OB (OB  10)

Priority class:    2

Current OB no. and priority class:

Requested OB: Program execution error OB (OB85)

Priority class: 26

Internal error, Incoming event

11:05:00.000 AM  01/27/2021

(Coding: 16# 35A1  1A55  C350  1001  1111  020A)

每次触发的时间是一致的，最近的诊断信息中提示1月 25 日、1 月 27 日、2 月 2 日都出现故障，从客户处了解到，这几天晚上没关机就出报警，分析下来应该是每天都是 11:05 出故障。

最后发现 CPU属性里将Time-of-Day interrupts 设置为每天一次中断，时间就是11:05 分，而在程序中并没有 OB10，所以PLC 就停机了，问题终于找到了。