s7_ program

[robert mooli]

Hi plc people out there , i need help from any one , we have siemens s7-400 installed ,i have tried to follow up the user programme successfully but now i want to ADD
an input (speed sensor)to monitor a chain conveyor in FBD, how do i go about it, i know about DBs,FBs&OBs etc
txs

 

[fribeiro]

Hi Robert,

Several issues you must take before improve the change.
First, try to identify other chain conveyor with speed sensor, so you can be based in the way you will do it.
Second, search in the user program where you will make the change.
Third, you need a new input, is there inputs available in I/O modules?
Fourth, FBD is just a way to represent the user program, you can change to STL or LAD if its more familiar to you.

Keep in touch,

 

[JesperMP]

The answer relies on the programming style of the existing program.

Is the existing program made with FB + Instance DB for the existing conveyor "object" ?
Or is it made with "regular" code ?

You can attach a zip file with the existing project.
Use the "archive" function in STEP7 to create the zip file.

 

[robert mooli]

ok shld i create my memory bit for this input in a data block or in an instant block and whats the diff.& do i need to make a fresh block call in OB1 . for ex i shall insert a network in an existing FB, corresponding to i think DB or IDB ie when (according to my logic)when chain conveyor is ok sets ths meomry bit to true & when ko goes to false, now how do make sure that this is executed by the prog. txs GUYs

 

[JesperMP]

robert,

the reason that I ask about how the existing program is made, is that your modification must be implemented in the existing program.
If the original programmer has made the program with socalled "reusable code", then he has probably made a generic "conveyor" program block in an FB. Then he has called that FB (maybe in OB1) and assigned an instance DB for that particular conveyor.
To make a change to the program made with reusable code isnt trivial so it is best if we have a peek at the program before making any further suggestions.

If reusable code has been used, then there is a chance that there is allready an input on the FB for a speed sensor.
This I say because "conveyor" and "speed sensor" is a very common combination.

The best you can do now, is to use the "archive" function in STEP7 to create a zip file of the project, and then attach that zip file in a new post.

 

[robert mooli]

Thanks Jesper
unfortunately i cant create a zip file of the project but what i see the existing prog. for chain conveyor( object )yah he created an FB + instant DB , called this in OB1 ie call FBxx,DByy in OB1 and whats a reusable code how do you know the prog has a rc?

 

[RMA]

Robert,

In the Simatic Manager under the "File" menu you'll find the archive command. If you click on this it will create a Zip file of the whole project under the (stripped down to 8 characters version of the) project name. Make a note of which directory it's going to be stored in, or modify the target directory to some directory that suits you. You can then use the attach button under the edit box to append the zip file to your post.

Regards

Roy

 

[robert mooli]

Hi thanks guys for your tips
i made it