Skip to Content

Register Login

Default Header

(header konnte nicht geladen werden)

Navigation

Differences between Function Block (FB) and Function (FC)

Created by: JTH at: 8/6/2007 5:13 PM (9 Replies)

Rating (6)

Thanks 4

10 Entries

8/6/2007 5:13 PM	Rate (1)
JTH Posts: 2 Rating: (1)	I have only used FC´s on my projects and I am wondering what is the main usage of FB? So what can i put in FB. FC is full of booleans,timers etc... Please advice me!
JTH Posts: 2 Rating: (1)
Suggestion To thank Quote Answer

8/6/2007 7:38 PM	Rate (1)
J_Bell Posts: 5822 Rating: (412)	Dear JTH, one huge advantage of the FB is the Instance DB. It allows you to have Memory directly dedicated to the FB itself. This is very important if you want to forward Data from one OB 1 cycle to the next one. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users MOHSENM Reza.71

8/10/2007 4:28 AM	Rate (0)
ivan_euler Posts: 54 Rating: (0)	thats right FC does not have memory block while FB requires instance Data Block for exercution....During every cycle FC losses its contens while the FB gets its memory to its associated block...FC is commonly used in arithmetic calculation and etc...
ivan_euler Posts: 54 Rating: (0)
Suggestion To thank Quote Answer

8/10/2007 6:14 AM	Rate (1)
Dec Gold Expert Joined: 5/19/2006 Last visit: 10/13/2025 Posts: 550 Rating: (107)	One other advantage of FB over FC (from STEP7 programming perspective) is passing the parameters in/out to the function. In FC the calling block push the variable into OBstack (limited in size) where with FBs, variable are passedusing instance DB. This is done in STEP7 language editors (STL, LAD) using AR2 register behind the scene. Dec

Suggestion To thank Quote Answer

8/12/2007 3:14 PM	Rate (0)
Late Platinum Member Joined: 1/7/2006 Last visit: 5/11/2025 Posts: 2705 Rating: (321)	One other advantage of a FB is that you may use multiple instance FunctionBlocks whereby all data is stored in one Datablock even when you use more FB's in one FB.
	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

7/15/2011 12:21 PM	Rate (0)
pachu Posts: 48 Rating: (0)	hi, Can you tell me when we use FB?
pachu Posts: 48 Rating: (0)
Suggestion To thank Quote Answer

7/15/2011 12:52 PM	Rate (0)
MM1234 Posts: 270 Rating: (53)	Hello pachu, I believe you should use FBs instead of FCs simply when it's more beneficial for you programming wise. Look at the differences/advantages others mentioned in this thread and there you see, when you are going to use it immediately.
MM1234 Posts: 270 Rating: (53)
Suggestion To thank Quote Answer

7/15/2011 1:27 PM	Rate (3)
umencho Grandmaster Joined: 3/21/2006 Last visit: 10/16/2025 Posts: 10239 Rating: (1183)	Hello, An old discussions here with the same issue: 1. Difference between FB and FC's 2. FB FC Best regards, Hristo MIhalev

Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users Ayman Elotaify C-3PO

7/18/2011 11:13 AM	Rate (0)
pachu Posts: 48 Rating: (0)	hi , thank you very much for that link.Now i think i have got good understanding of Fc and Fb. We can use Fb and Fc more for programs which repeat frequently right? As we are using it multiple times,how we can monitor the value of a particular Db? if i change anything in any Fb it will affect all sequences where ever it is called right? I just started learning Step7,so if my questions seems to be silly please forgive.
pachu Posts: 48 Rating: (0)
Suggestion To thank Quote Answer

7/18/2011 11:23 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 12/4/2025 Posts: 6885 Rating: (1368)	Dear pachu pachu We can use Fb and Fc more for programs which repeat frequently right? Yes pachu As we are using it multiple times,how we can monitor the value of a particular Db? For each FB,you assign a DB,You can individually monitor any variable in any DB in a VAT(variable table) pachu if i change anything in any Fb it will affect all sequences where ever it is called right? How do you update invalid block calls (time stamp conflicts) in calling blocks? How do you perform a block-consistency check following changes in the STEP 7 program? Regards
	Last edited by: hdhosseini at: 7/18/2011 11:25 AM Demo Channel on Youtube
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on