Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

SIMATIC S7-300 Online Connection Blocks the Program Cycle !!

Created by: Kerem at: 1/10/2011 9:24 PM (4 Replies)

Rating (0)

Thanks 0

5 Entries

1/10/2011 9:24 PM	Rate (0)
Kerem Posts: 4 Rating: (0)	Hello, We have a workstation which has the CPU of 315-2DP in our assemblage line. My problem is: When I try to get online to a specific FB, inmy case this FB is FB14, the program cycle blocks, the machine does notoperatein the way which it has to andsoon the system gets intoan error state. If I have to explain more detail, the workstation operates without any problem unless we connect and get online to FB14. The amazingandthe interestingthing is; this is the only FB which affects the program cycle in the way I explained above. I havegot onlineeach ofthe other FCs or FBs and tested the function of the machine while I was online. Ihave not observed any kind of cycle blockage problem as we havefaced in the caseof FB14. I can say and know that, this FB is not a special or a protected function block. It is an ordinary FB as the other FBs used in the program. Also, I observed from the VAT table that, the outputs which has been used in this FB, blinks rapidly at the moment when Iam online. If there isanyone who has experienced such kind of problem or who could help me to find the solution of this problem, It would really be great to share the solutions or experiences.. Best Regards, Kerem..
Kerem Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

1/11/2011 12:07 PM	Rate (0)
jacek d Platinum Expert Joined: 9/23/2005 Last visit: 11/12/2024 Posts: 4785 Rating: (730)	Whatever this FB does, it does a lot. At least it seams to be so. But instead of worrying about this, try to change the CPU operating mode from Test to Process in HWConfig and download changed configuration.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
Suggestion To thank Quote Answer

1/14/2011 8:46 AM	Rate (0)
Goran_ Posts: 141 Rating: (0)	KeremKu has the same problem like me, so I hope its ok for me to jump into the discussion. jacek d, what do you mean by "does a lot"? My function reads and writes data from DB using OPN command. In this case, it reads appox 10 values and writes approx 10 values. It uses few miliseconds to execute the function. Setting to Process mode will surely prevent PLC to go to stop mode, but that still prevents me from debugging...
Goran_ Posts: 141 Rating: (0)
Suggestion To thank Quote Answer

1/14/2011 9:27 AM	Rate (0)
jacek d Platinum Expert Joined: 9/23/2005 Last visit: 11/12/2024 Posts: 4785 Rating: (730)	Well, I mean that this function does something excessive with the data. You want to have look at this all and here is a bottle neck. Transfering all this to being displayed on your screen takes time. If you don't wanna use Process Mode - extend your watchdog, split your function, do not try to monitor loops. And monitor only one block at time. However common sense says - don't forget to switch to Process Mode when you are done. BTW, PC/TS Adapters used to be veeeeryyyy sloooooow...
	Last edited by: jacek d at: 1/14/2011 9:34 AM Last edited by: jacek d at: 1/14/2011 9:32 AM Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
Suggestion To thank Quote Answer

1/16/2011 11:06 PM	Rate (0)
Wild Bull Posts: 30 Rating: (1)	I have seen the same problem when programming in STL. When there are many instructions in one network and there is less than 15% free memory in the PLC. When you go online, the scan time will exceed the 150 ms watch dog timer and fault the processor. I have duplicated the problem with different CPUs, including 318, 315, IM151, Make sure none of the networks have to many instructions and stay away from a loop within a loop if you can. I have never seen this problem when the code was in ladder.
Wild Bull Posts: 30 Rating: (1)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on