Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Direct access I/O

Created by: ShahinM at: 1/21/2009 2:14 PM (7 Replies)

Rating (0)

Thanks 0

8 Entries

1/21/2009 2:14 PM	Rate (0)
ShahinM Silver Member Joined: 11/8/2005 Last visit: 5/31/2023 Posts: 335 Rating: (3)	Is there anyway to read input or put output in middle of OB1?

Suggestion To thank Quote Answer

1/21/2009 2:18 PM	Rate (0)
UMENCHO Diamond Member Joined: 3/21/2006 Last visit: 4/12/2023 Posts: 10221 Rating: (1176)	Hello SM, Can you continue and explain with more details your question? regards

Suggestion To thank Quote Answer

1/21/2009 2:35 PM	Rate (0)
ShahinM Silver Member Joined: 11/8/2005 Last visit: 5/31/2023 Posts: 335 Rating: (3)	In my program,cycle time is very long and in this time, some input may change.I want to monitor them.

Suggestion To thank Quote Answer

1/21/2009 2:57 PM	Rate (0)
Zenta Silver Member Joined: 10/12/2006 Last visit: 5/24/2023 Posts: 206 Rating: (25)	SM Is there anyway to read input or put output in middle of OB1? Yes. You can read PIW(PEW) and you can write PQW(PAW) Regards Zenta

Suggestion To thank Quote Answer

1/21/2009 3:57 PM	Rate (0)
ShahinM Silver Member Joined: 11/8/2005 Last visit: 5/31/2023 Posts: 335 Rating: (3)	So in this situation reading will happen in the start of OB1 and writing to output will happen in end of OB1.But I need to read and write in middle of OB1 not in the beginning and end of OB1.

Suggestion To thank Quote Answer

1/21/2009 4:37 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 3/8/2023 Posts: 703 Rating: (96)	Hello, as Zenta wrote, you can access directly the peripheryaddress PIx or PQx from any part of program, only restriction is that it's impossible to access bit address, the smallest unit is byte, but it shouldn't be problem. Regards Sydney
	Last edited by: Sydney at: 1/21/2009 4:40 PM language corrections ;)
Suggestion To thank Quote Answer

1/21/2009 9:31 PM	Rate (0)
bit7 Experienced Member Joined: 7/26/2008 Last visit: 6/6/2023 Posts: 81 Rating: (16)	It is of course near impossible to determine where in the scan time of OB1 to scan the fast input. Use a fast cyclic OB to scan the input and code to react, but keep the scan time of the code short. Again, L IW comes from Input Image, L PIW comes directly from hardware.

Suggestion To thank Quote Answer

1/21/2009 9:40 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 2/16/2023 Posts: 2705 Rating: (311)	SM So in this situation reading will happen in the start of OB1 and writing to output will happen in end of OB1.But I need to read and write in middle of OB1 not in the beginning and end of OB1. Hi, Maybe an strange question, but why didn't you use a Interrupt DI, so the inputs are coming very quick in OB40....OB47 For example the 6ES7 321-7BH01-0AB0. If the call of the inputs on several places in OB1 isn't fast enough then it might be easy to spent some extra money for a hardware interrupt input card.
	Last edited by: Late at: 1/21/2009 9:41 PM 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

|

Share this page:

Share this page on...

Follow us on