new guy need help understanding FFB's

[PLC newbe351]

i am trying understand a program in Concept. and i don't get useing WORD_TO_BIT, BIT_TO_WORD,BIT_TO_BYTE...so on, FFB's. any help on why to use them.

Thanks in advance

 

[L D[AR2P#0.0]]

One example of word to bit would be reading a drive status word and then mapping the status word bits to individual boolean variables (Running, Fault, AtSpeed, Ready etc).

 

[Chris S]

One reason to use them is for Messaging or information exchange. It is sometimes easier, and most times more efficent memory use to exchange data between 2 PLC's in word format. Instead of transfering 16 different data points individualy you would pack them into a 16-bit word and send it across as the word. This creates better network use. In my experiance it starts getting very usefull after you have 4 or more PLC's on one network. You will notice slowdown of information to and from your OP's or PV if you dont start using some sort of data management.

Also L D is absolutly correct. Many drives and other such external devices always pack there information into words and send them to you. This can be used in there native form or you can unpack them if you want. That all depends on if you want to train the maint techs or someone without alot of knowledge in programming PLC to understand what the .X means.

 

[kdcui]

To give an example regarding devices packing status into words:

When communicating over protocols, such as DeviceNet, a VFD might broadcast it's status on a word. Each individual bit (or groups of bits) would be indicative of some status of the VFD (fault, LCP status, Hand/Off/Auto, etc...).

From there you can buffer each bit in the word to an appropriate tag so you can deal with it individually.

As to what bits do what on the word, that info is usually supplied by the manufacturer of the device.

Conversely, commands to the VFD may be conveyed in word format. So you would toggle a certain bit in a command word to the VFD to turn it off, reset a fault, etc...

 

[PLC newbe351]

this makes since....i was confused because when the bits were changed to word it was not used anywhere in the program. so this must be how it is communicating with the servo drive.


next question..

how do i now find in the drive where these words are being used?
using Unilink with Lexium drive.

 

[Chris S]

this makes since....i was confused because when the bits were changed to word it was not used anywhere in the program. so this must be how it is communicating with the servo drive.


next question..

how do i now find in the drive where these words are being used?
using Unilink with Lexium drive.

In order for us to know that you will have to let us know what Drie and Model # it is. There should be a manual somewhere that will explain where and what they do.

 

[kdcui]

http://www.schneider-electric.com/s.../function-presentation.page?p_function_id=19#

If I got the link right, the Lexium servo models are at the bottom. If you go to Tech Literature there are some manual you can download, and it shows the drive configuration.

 

[PLC newbe351]

thanks guysyou have all been a big help

 

[AlfredoQuintero]

xeniaty again, trolling. Maybe this accont should be blocked?

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Should this account better be blocked?

 

[geniusintraining]

Should this account better be blocked?

Done... you can also click on "report post" on the lower left and we will see if faster, then we can delete the post and also band the user

Thank you :site:

 

[AlfredoQuintero]

I did not know about this "report post" feature. I can't see this feature in the lower left of my screen. I am using the normal style.

 

[geniusintraining]

I can't see this feature in the lower left of my screen.

Do you see the whistle?