Beckhoff wire tag/labeling convention?

[busarider29]

I am new to Beckhoff PLC hardware.  I'm in the process of ordering components and drawing the prints.  I'm looking for norms/conventions that users use for wire labeling to/from the Beckhoff I/O as well as tagging the individual EtherCAT slices.  Beckhoff has a plethora of individual tags that you can purchase that snap onto the I/O slices, but I'm lost as to which ones to get, etc.  For our AB controlled machines, our typical practice is to label the wire to the I/O point as the specific physical I/O (I:02/04, I:02/05, etc...).

[Archie]

Over the years I've developed a numbering system that resembles the AB SLC style addressing. I use this numbering for addressing within the program and also for wire numbers. This is the scheme I use:

- First 2 digits is node number. If it is local IO, these will be 0.
- Next 2 digits will be slot number
- Fifth digit is byte number. Will be 0 for 8 point or less digital cards.

For example:

%IX01050.0

would be a digital input rack node 01, slot 5, bit 0

Another example:

%QW02032    (I actually use %QW2032, but show the leading zero to make it easier to understand)

would be rack node 02, slot 03, and second analog output. Analogs generally use 2 bytes, so the last digit would be 0,2,4, etc


For wire numbering, I leave off the % and X, W, or B. So my wire number would be Q2032

You can see one advantage to this scheme is easy identification of where the address physically resides. Another advantage is this scheme is compatible with ARM based processors such as the CX8090, which only allow even number addresses.

The single disadvantage I have found is if you make changes often and insert cards in the middle of the rack. This will then make your slot numbers no longer line up with the address. Although since there is a 10 byte jump in between slot, you can still maintain consecutive order.

[busarider29]

Thanks Archie.  That will work.  Also, do you ever use the little tags that snap into the top of each slice that appear to be for identification purposes of the slice/s themselves?  If so, what's your convention for that? 

Thanks,
Don

[Archie]

I do not use the snap in labels because the back plate panels have all of the information printed on them. Attached is a pictureof a panel partially built where you can see what I mean. Note this panel was designed before my addressing scheme was fully developed, so the addresses do not comply with what I described above.

[busarider29]

Ok, gotcha.  That's slick.  Wish we could do that here but I'd be too afraid to do it with the changes that sometimes happen with our machines.  When you say you use the same numbering convention in the program (as well as wire labeling), what specifically are you referring to?  As I'm new to TwinCAT (Using TC3), my understanding is you pick a variable name and then link it to the physical I/O.  Is there somewhere specifically within the program where you are also entering the wire number for that I/O?  Just trying to pick up any little bit of helpful hints as I learn this new platform.

Thanks,
Don

[Archie]

I haven't moved to TC3 yet, but I assume the principles are still the same.

For each address you link to a physical point, you must assign an address. Using the example I mention above, the variable declaration would look something like this:

MyDigitalInput AT %IX1050.0 : BOOL;

My wire number for this input would be I1050.0

[busarider29]

Ohhhh.....Ok, I got it.  You are giving the I/O point a specific descriptor in your declaration.  I'll probably revert to doing that too.  My declarations look like so:

MyDigitalInput AT %I*    :     BOOL;

Thanks for the feedback.

[Archie]

I used to use the wildcard declarations until one day I added a new variable which then re-assigned all of the wildcard addresses which in turn broke the links. The end result was shutting down over half a plant before I knew what happened.