Allen Bradley Addresses

Hello,

I am working on a project to convert an older Allen Bradley PLC5 to a CompactLogix. The existing electrical drawings use PLC I/O wire numbers that correlate to the Rack-Slot-Point address (i.e. 012400). This was done as a very intuitive means to look at wire label and search in PLC logic. My questions is after I convert this project to a CompactLogix PLC, I do not want to keep this vintage addressing schema. The new address in the Logix family is not very concise (i.e. Local.I..). Is there a industry common nomenclature used with the new Logix PLCs that is easily decoded by maintenance to search in the PLC code? I understand Aliasing and how to implement. This question is more a naming or nomenclature standard you have seen in the industry.

Thanks,

Greg

I have seen some programmers use LI#.# (Digital Inputs) and LO#.# (Digital Outputs). L stands for Logical and I/O stands for Input or Output. The first # is the card # and the last # is the terminal ID. This works OK but was curious on what others were using.

Thanks,

Greg

samsung1974 said:

Hello,

I am working on a project to convert an older Allen Bradley PLC5 to a CompactLogix. The existing electrical drawings use PLC I/O wire numbers that correlate to the Rack-Slot-Point address (i.e. 012400). This was done as a very intuitive means to look at wire label and search in PLC logic. My questions is after I convert this project to a CompactLogix PLC, I do not want to keep this vintage addressing schema. The new address in the Logix family is not very concise (i.e. Local.I..). Is there a industry common nomenclature used with the new Logix PLCs that is easily decoded by maintenance to search in the PLC code? I understand Aliasing and how to implement. This question is more a naming or nomenclature standard you have seen in the industry.

Thanks,

Greg

Click to expand...

If you kept the existing wire-numbering scheme, would you get away with not having to re-do the field wiring schematics ?

You are correct. Part of the controller upgrade would include new wire labels. The existing are faded and missing. If I take the time to replace the PLC with new hardware I assume I would want to follow the newer convention for PLC I/O wiring tag nomenclature.

Thanks,

Greg

A word of caution.

Everyone is used to the current wiring diagrams and numbering system.
when you replace the plc and wiring, you must train everyone on the new system and schematics, get all the old schematics, and be available for 2-3 weeks on a 24/7 basis, and have troubleshooting charts available and rewrite the existing manuals (if any) to the new plc structure.

regards,
james

samsung1974 said:

I have seen some programmers use LI#.# (Digital Inputs) and LO#.# (Digital Outputs). L stands for Logical and I/O stands for Input or Output. The first # is the card # and the last # is the terminal ID. This works OK but was curious on what others were using.

Thanks,

Greg

Click to expand...

I use "L" as well, but I always assumed it stands for "Local".

For the 7th input on the first card on a local chassis, an input address might be Local:1:I.Data.7, in which case I would label the wire L01i07 (Local rack, Slot 1, Input 7). Nice and intuitive.

If I have remote racks, the "L" becomes "Xn:", where n is the "node" number of the remote rack. So the same input on remote rack #3 will be numbered "X3:01i07".

There are plenty of ways to do it, but to me this way is nice and simple and prevents me from having to break out the drawings 90% of the time. It still follows the "Rack-Slot-Number" format that everyone on your site is used to, it's just slightly updated to align with the way the Logix 5000 platform deals with I/O addressing, instead of how the PLC-5 platform handles it. If your techs are used to Rack-Slot-Number, and they are well-trained enough to understand CLX addressing, they should pick it up in no time.

If it were me, I would keep the naming structure the same as it was. This would be especially true of other machines in the facility use the the same naming conventions. Bubba is familiar with how it is done now, and isn't going to appreciate having the standards changed.

Bubba.

I would agree in keeping the existing numbering.

Having just completed a 2 PLC5 to 1 ControlLogix upgrade, with 35 Flex I/O racks (gone from RIO to Ethernet) it was stressed to me that the guys on the plant maintenance know the numbers.

The new rack IP addresses reflected the old RIO rack number and none of the connecting wires were changed, so drawing changes were kept to rack adapters and other rack hardware, along with network cabling,.

If you are redrawing everything, I'd use Page/Line # for all wires.

I replaced an older system with a new compact logix a while back and if the I/O was local I just numbered it I6.0, I6.1, O8.0, etc. The remote I/O I used X11-I2.1, X12-O1.0, etc.

The numbering system we use is just the slot number and the input(or output) number. For example, slot one using 100, 101...115 etc. Slot 10 is 1001, 1002, etc. For isolated outputs we add an A and B, for example 1101A, 1101B, 1102A, 1102B. Analogs get a + and - added to them.

This works very well for us, but we have almost no circuitry that does not go to PLC I/O with the exception of the estop string.

rdrast said:

If you are redrawing everything, I'd use Page/Line # for all wires.

Click to expand...

I agree. I always use page/line #. That way you know exactly where to look for how to wire. I have seen where they use line/page number on field side and IO addressing on panel side of terminal block. I generally do not like to change wire numbers across a terminal.

WIre number 110-11 tells me that on page 110, line 11

Keep wires same. Use aliasing to make the names in Logix match what the PLC5 names used to be, that way as far as maintenance is concerned as little as possible has changed.