Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

S7-300 OB90 background cycle?

Created by: mhkocak at: 8/10/2009 4:49 PM (3 Replies)

Rating (0)

Thanks 0

4 Entries

8/10/2009 4:49 PM	Rate (0)
mhkocak Advanced Member Joined: 1/8/2009 Last visit: 6/5/2024 Posts: 43 Rating: (0)	Hello, As far as I understand, it is not possible to use OB90 background cycle in S7 300 CPUs. Because it is not enabled to change "Minimum scan cycle time" in HW Config. In my program, some parts should run fast and I/O should be refreshed fast. Some parts of program can run slower. - How can I organize in OBs these 2 groups? - If I use cyclic OBs for fast group like OB30, can I update I/Os synchronous to OB30? If I can not update I/Os fast, it wouldnt be meaningful to run some parts of program fast. Thanks to the experienced people. mhkocak

Suggestion To thank Quote Answer

8/10/2009 6:03 PM	Rate (0)
H-H Platinum Member Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating: (309)	Hello mhkocak, mhkocak If I use cyclic OBs for fast group like OB30, can I update I/Os synchronous to OB30? Just to tell you, S7-400 has typically what you want. you canassignsome modules to a partition of process image which you assign to a cyclic interrupt organization block. This partition of process image gets refreshed synchronously with its OB. There's also SFC26 & SFC27 for refreshing process image when you need. Back to S7-300, You can manouvre with peripheral addressing to access modules directly. The point is, does it really worth the effort? S7-300 means to me an average scan cycle of15 to 30msec (By all means not exceeding 100msec). Do you have inputs that can change faster than your cycle time? I don't know what kind of inputs you have but if you have inputs with very fast change rates (High frequency) then there are some modules for that and if you have some inputs that may do harm if they are not caught in time, you can use hardware interrupt modules for them. Best regards. H-H

Suggestion To thank Quote Answer

8/10/2009 8:23 PM	Rate (0)
mhkocak Advanced Member Joined: 1/8/2009 Last visit: 6/5/2024 Posts: 43 Rating: (0)	Hello H-H, Peripheral addressing seems to be a good solution for direct read and write I/Os. In my application, the machines cycle time is minimum 1200 ms. And 1 machine cycle is 360 degrees. So 1 degree is 3,33 ms. For precise timing of the machine, cycle time of the controller should be as short as possible. I think it shouldnt be more than 10 ms. I am considering another alternative with OB61, SFC126, SFC127. mhkocak

Suggestion To thank Quote Answer

8/11/2009 6:52 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	Basically you should implement such kind of things on simotion/sinamics. Are for your request - best solution i guess is OB35 containing SMALL programm (maybe with PIW, maybe with UPDATE_PI). Rest should be proceed in OB1. Then you can manipulate with OB35 calling time.... Maybe there are other ways - please decribe what are you trying to implement.
Aret Posts: 2348 Rating: (265)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on