Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Check FB/FC code at runtime?

Created by: krushia at: 8/31/2006 7:28 AM (26 Replies)

Rating (13)

Thanks 1

Result pages:: |; 1 | 2 | 3; |

27 Entries

Entries per page: 10 | 20 | all

8/31/2006 7:28 AM	Rate (0)
krushia Member Joined: 8/31/2006 Last visit: 9/11/2008 Posts: 6 Rating: (0)	I am wondering if there is any way to create some PLC code to gather basic data on other FC/FB blocks in the PLC. At the minimum I would like to determine the size of the code in each block. Similar to the SFC24 "TEST_DB" function, but for checking code. Regards - Ken

Suggestion To thank Quote Answer

8/31/2006 5:46 PM	Rate (0)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 11/11/2024 Posts: 4351 Rating: (1452)	Hi, do you want create a program code, by user program, into a PLC or do you want create program code into a PC (for example, with excel)?
	Denilson Pegaia Siemens Industry Sector Technical Support
Suggestion To thank Quote Answer

8/31/2006 11:39 PM	Rate (0)
krushia Member Joined: 8/31/2006 Last visit: 9/11/2008 Posts: 6 Rating: (0)	I want to write a FB that will verify the checksum of the other FC/FB blocks in the PLC to make sure the code is unmodified. Basically I need to know if it is possible to have the PLC check it's own code.

Suggestion To thank Quote Answer

9/1/2006 12:12 AM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 11/17/2023 Posts: 2705 Rating: (318)	Hi Krushia, As far I know the CPU is already checking that and goes in to STOP with a error when something wents wromg in the memory. [:o] With the CPU414H / CPU417H there is also a possibility to repair the bits that fall down, this have EDC memory which stands for error detection and correcting memory. There are some extra bits by every word in the memory where the polynom is put in to, wenn there are changing some bits then with the polynom the bit that changes is detected and can be corrected. With the normal CPUs it is detected but the CPU goes into STOP. [;)]
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
Suggestion To thank Quote Answer

9/1/2006 5:54 PM	Rate (0)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 11/11/2024 Posts: 4351 Rating: (1452)	Hi, I think that you mind some think like a know how protection of your program. So, ... I don't know some feature, like check a software signature in a standard software (only in Distributed Safety Sistem), to avoid a unauthorisated change. My Sugestions: 1 - Use a Knowhowprotection technology. (maybe you will say that some hackers can krack it, but if they willdo that, certainly they will kracka check summ protection). 2 - Use password in your CPU (HW config). You can set total restriction, or read-only restriction. 3 - You can read the MMC serial number and use it in your logic, so an unautorizate copy will not run in other sistem.
	Denilson Pegaia Siemens Industry Sector Technical Support
Suggestion To thank Quote Answer

9/1/2006 7:49 PM	Rate (0)
krushia Member Joined: 8/31/2006 Last visit: 9/11/2008 Posts: 6 Rating: (0)	Yes, I need this to have a sort of "know how protection" in the PLC. None of your suggestions apply. I need to have the ability to program a FB that will generate a CRC for the other FBs in the PLC and display the hash results on the HMI. This is to verify that the machine manufacturers are using the correct standard FBs I have written. So there is no standard way to access code information from a FB? That is too bad. I will do it another way then, by having the standard FBs trigger a programming error at certain points, and have another FB compare the instruction addresses in the diagnostic information to determine block size. If anyone has more info on obtaining code information from within the PLC program, please post here. Regards, Ken

Suggestion To thank Quote Answer

9/3/2006 5:28 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 11/17/2023 Posts: 2705 Rating: (318)	Hi Krushia, As far I know there are no possibilitys to do this, I have tought there might be a SSL-list, but I didn't find it. If you want to make a know_how_protect, then you may read out the MMC card and the number of the CPU and make a block that is protected with the code for the protection in the block.
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
Suggestion To thank Quote Answer

9/5/2006 1:10 PM	Rate (0)
Aret Posts: 2348 Rating: (264)	try this System Software for S7-300/400 System and Standard Functions Chapter 31.7 SSL-ID W#16#xy13 - Memory Areas To read from this list you will need SFC51 2Pegaia, >1 - Use a Knowhowprotection technology. (maybe you will say that some hackers can krack it, but if they willdo that, certainly they will kracka check summ protection). Not quite right. I would say that searching in other's STL code for a particular part can be harder (especially if it's written in SCL).
Aret Posts: 2348 Rating: (264)	Last edited by: Aret at: 9/5/2006 1:15 PM
Suggestion To thank Quote Answer

9/7/2006 6:53 AM	Rate (0)
Dec Gold Expert Joined: 5/19/2006 Last visit: 10/23/2024 Posts: 549 Rating: (107)	Hi Ken, Check thisand figure-out how its protected [8)] Attached is a small STEP7 program with FC1 thatcalculates a + b = c. You download FC1 with copy/paste from SIMATIC Manager with offline/online blocks folder. Never change, save or downloadFC1in LAD/STL editor -> you will tripe the CPU (or wipeout the whole function). You can freely edit/download/test OB1 thoughor any other block. Dec Attachment Prot.zip (765 Downloads)
	Last edited by: Dec at: 9/7/2006 8:27 AM Last edited by: Dec at: 9/7/2006 8:20 AM Last edited by: Dec at: 9/7/2006 7:43 AM
Suggestion To thank Quote Answer

9/7/2006 1:13 PM	Rate (0)
Aret Posts: 2348 Rating: (264)	Well, this function only stops CPU. Maybe there is something i didn't notice? As far as i can understand the question was to determine if any block (or particular block) has chaged. The only thing i can suggest - check free code space of the CPU. If it changed => somebody got into the programm. But this protection is pretty bad - you can't set it on particular block. Also you can't check if one single bit has changed (if size didnt changed).
Aret Posts: 2348 Rating: (264)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on