新工程用原来的老程序，组态和程序都下载后SF灯亮，系统运行正常。查看诊断信息，诊断信息内容为：
Diagnostic buffer of module CPU 315-2 DP

Order No./ Des cription Component Version
6ES7 315-2AH14-0AB0 Hardware 4
- - - Firmware V 3.3.7
Boot Loader Firmware expansion A 32.9.9

Rack: 0
Slot: 2


Event 1 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 424
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.619 AM 03/20/2013


Event 2 of 10: Event ID 16# 2943
I/O access error, writing
P area, word access, Access address: 450
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.615 AM 03/20/2013


Event 3 of 10: Event ID 16# 2943
I/O access error, writing
P area, word access, Access address: 452
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 4 of 10: Event ID 16# 2943
I/O access error, writing
P area, word access, Access address: 452
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 5 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 436
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 6 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 436
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 7 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 436
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 8 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 436
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 9 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 430
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013


Event 10 of 10: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 430
Requested OB: I/O access error OB (OB122)
Priority class: 1
External error, Incoming event
08:50:35.614 AM 03/20/2013
上网查找了相关帖子，在程序里开始查找PIW430、PIW436、PIW424并删除，找PIW450、PIW452没找到，遂找PQW450、PQW452并删除，重新下载程序后SF灯灭。问题解决