Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

I/O address ranges

Created by: iman12 at: 4/21/2014 8:34 AM (16 Replies)

Rating (2)

Thanks 10

Result pages:: |; 1 | 2; |

17 Entries

Entries per page: 10 | all

4/21/2014 8:34 AM	Rate (0)
iman12 Member Joined: 5/26/2012 Last visit: 8/4/2021 Posts: 16 Rating: (0)	Hey guys, I saw the S7-400 CPUs broushure. In address range field, it has two section. One of them is I/O and the other one is I/O process image. The values are different and I don't know why. I know the consept of I/O process image and I/O(direct access), but I don't understand why they are different in size of addressable range. Does it mean, we cannot use all the I/Os in process image I/O??

Suggestion To thank Quote Answer

4/21/2014 10:02 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	iman12 ... Does it mean, we cannot use all the I/Os in process image I/O?? Yes, that is what it means. I/O outside of process Image you can only adress by byte, word, doubleword. not by Bit.
IBN-Service Posts: 8946 Rating: (999)
Suggestion To thank Quote Answer

4/21/2014 12:28 PM	Rate (0)
iman12 Member Joined: 5/26/2012 Last visit: 8/4/2021 Posts: 16 Rating: (0)	And do we have a direct access to all I/Os which are not in the Process Image I/O?

Suggestion To thank Quote Answer

4/21/2014 1:45 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	iman12 And do we have a direct access to all I/Os which are not in the Process Image I/O? Yes. Example: L PIW 2000 T PQB 900 Remember, that most newer CPU allow you to increase the process image in hadware configuration as well.
IBN-Service Posts: 8946 Rating: (999)
Suggestion To thank Quote Answer

4/21/2014 1:50 PM	Rate (0)
VVago Posts: 784 Rating: (52)	IBN-Service iman12 ... Does it mean, we cannot use all the I/Os in process image I/O?? Hello IBN-Service, Sorry,What is the difference between I/O address and Process image I/O address? Best regards........
VVago Posts: 784 Rating: (52)
Suggestion To thank Quote Answer

4/21/2014 2:03 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	Eng. Mohamed IBN-Service iman12 ... Does it mean, we cannot use all the I/Os in process image I/O?? Hello IBN-Service, Sorry,What is the difference between I/O address and Process image I/O address? Best regards........ You will find a very good introduction in manual. A short overview for Step7 V5.5: Any scan of OB1, FIRST of all, the System will read all I/O that are declared as "process Image" to a separate memory location, that is called "process Image (PI)". ONLY the adresses that are stored inside the PI can be adressed by using I 0.0, Q 100.6, IW 20, QB 7ect. ALL other I/O that are not in PI needsusing the "P" prefix, bits are not possible. So you have toadress PIW xxx, PQW yyy ect. Advantage of PI is: You can access bits. Because PI - Memory location is "near by", it is very fast. The status of any PI Signal will NOT Change during one OB1 scan. Reading / writing Peripherie adress outside the PI(PiWxxx)needsmore time because CPU must fetch the signals from "somewhere" (Profibus, I/O module, whatever). Signal Status of P-adresses may change during an OB1 scan.
IBN-Service Posts: 8946 Rating: (999)
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users S7 AUTOMAN VVago

4/21/2014 2:47 PM	Rate (1)
VVago Posts: 784 Rating: (52)	Hello IBN-Service, Thanks for your concerning. Kindly check the following idea: PI"Process image":for digital modules. PIW,PQW:for analoque modules,Profibus and other devices....... Best regards.....
VVago Posts: 784 Rating: (52)
Suggestion To thank Quote Answer

4/21/2014 4:45 PM	Rate (0)
AUS_MB Posts: 45 Rating: (0)	It is typically but not always the case that analogs etc will not use the process image However alot depends on the size of your process image. I have seen many larger processors where all access uses the process image. You can check in the hardware configuration offline if a peripheral device uses a process image partition (PIP) or if it does not. If it does not, then you will need to do peripheral access to get the data Even if data is mapped into the process image, peripheral access is still possible and can be common on scan time sensitive machines
AUS_MB Posts: 45 Rating: (0)
Suggestion To thank Quote Answer

4/21/2014 5:47 PM	Rate (0)
VVago Posts: 784 Rating: (52)	AUS_MB It is typically but not always the case that analogs etc will not use the process image However alot depends on the size of your process image. I have seen many larger processors where all access uses the process image. You can check in the hardware configuration offline if a peripheral device uses a process image partition (PIP) or if it does not. If it does not, then you will need to do peripheral access to get the data Even if data is mapped into the process image, peripheral access is still possible and can be common on scan time sensitive machines Thanks AUS_MB
VVago Posts: 784 Rating: (52)	Last edited by: Eng. Mohamed at: 4/22/2014 6:23 PM
Suggestion To thank Quote Answer

4/21/2014 5:54 PM	Rate (0)
VVago Posts: 784 Rating: (52)	Hello, Every think cleared now. Best regards.....
VVago Posts: 784 Rating: (52)	Last edited by: Eng. Mohamed at: 4/22/2014 6:30 PM
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users IBN-Service

|

Share this page:

Share this page on...

Follow us on