Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Counter Question

Created by: ronin237 at: 6/9/2009 10:42 PM (3 Replies)

Rating (0)

Thanks 0

4 Entries

6/9/2009 10:42 PM	Rate (0)
ronin237 Posts: 6 Rating: (2)	Hello All, I am porting a program from AB to Siemens Step 7. Since the S7 does not have a --\|ONS\|-- like Allen Bradley, and we are counting instances of a certain condition, I have opted to use the --(CU)-- Count up Coil in the Siemens since it triggers on the rising edge of RLO. Now my question is that I need to get that accumulation and send it to an HMI and store it. (we do the accumulation once pershift and keep data for 2 weeks) In AB you can access the data by using CX.Y.ACC where X.Y is the counter address. How do I do this with the Count Up Coil ? Thanks!
ronin237 Posts: 6 Rating: (2)
Suggestion To thank Quote Answer

6/9/2009 11:40 PM	Rate (0)
rit03 Silver Member Joined: 6/13/2006 Last visit: 2/11/2023 Posts: 341 Rating: (23)	ronin237 Hello All, I am porting a program from AB to Siemens Step 7. Since the S7 does not have a --\|ONS\|-- like Allen Bradley, and we are counting instances of a certain condition, I have opted to use the --(CU)-- Count up Coil in the Siemens since it triggers on the rising edge of RLO. Now my question is that I need to get that accumulation and send it to an HMI and store it. (we do the accumulation once pershift and keep data for 2 weeks) In AB you can access the data by using CX.Y.ACC where X.Y is the counter address. How do I do this with the Count Up Coil ? Thanks! You can achieve this by using SFB counter of step 7 instead of using CU. SFB uses instance data block to accumulate counter value and therefore can be used by user to use it anywhere else in the code. regards, rit03

Suggestion To thank Quote Answer

6/10/2009 11:30 AM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 3/8/2023 Posts: 703 Rating: (96)	Hello, you can also load value from the hardware counter in program and also mostly in SCADA, but itshigh limit is 999 and while restart of PLC it's normally reseted. When you use SFB0 "CTU" as suggested by rit03 the count value is stored in the DB so the acces is without problem anywhere, the value data type is INT so range is 32767 and you can decide if you reset it after PLC restart. For detailed information of this SFB use the online help. Regards Sydney

Suggestion To thank Quote Answer

6/10/2009 2:46 PM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 6/3/2023 Posts: 2966 Rating: (1025)	Hello ronin237 whiele there is nothing wrong with using counters you do of course have a "---\|ONS\|---" equivalent in S7 which you can use tofor example enable an "ADD Integer" calculation to achieve your counting. S7 calls these"Positive edge detection". Have a look at the Bit logic elements and you'll find a "---(P)---" symbol. Click on it and use "F1" to find out more about it. Btw, if you need to do your counting on anegative (falling) edge, you can use the "---(N)---" element. Lastley, there's two more instructions whichessentailly do thesame as the above two mentionedones and are called "POS" and "NEG" respectively. I'd stay away fromusing these too though asI find that they make code less readable than the "P" and "N" ones. Cheers Fritz
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on