Program Element Naming Conventions

[ndzied1]

In another thread (http://www.plctalk.net/qanda/showthread.php?t=15858) the topic of naming contacts was brushed upon. It actually can make understanding a program later straight forward or a bloddy mess.

What are the standards people follow in naming their elements?

I've mostly delt w/ RSLogix 500 so my answers will be skewed to it. For this I've almost exclusevely used Address based comments where the comment is the same wherever at address is used. This also allows Comments to follow a parent element such as the comment for a Timer will be used for the Timer status bits (unless a comment is specified for a specific bit such as the Timer Done bit).

For input comments I write the verb or action last

  Part

 Advance

 Cylinder

 Extended

[PROX_256]

+---] [----...

For Outputs I always try to put the Verb or action first

   Extend

    Part

   Advance

   Cylinder

   [SOL_352]

...---( )-----+

 

For I/O I've mostly used the RSLogix Symbols for the device reference on the schematic as shown above.

For groups of bits or registers that all relate to a common function, I try to us the first 2 lines of the comment like a mini title for the function:

    Auto Cycle

     Step 01

    -----------

    Index Table

     Started

    [AUTO_01]

...----( )---+

 

    Auto Cycle

     Step 02

    -----------

    Index Table

      Moving

    [AUTO_02]

...----( )---+

 

    Auto Cycle

     Step 03

    -----------

    Index Table

     Complete

    [AUTO_03]

...----( )---+

 

This is one of the biggest drawbacks I have with the IEC type programs. Especially in IL and ST, it is impossible to show a 5 line comment plus symbol for every BOOL that you use in the program. True, you can use creative tag names and this helps but it does not compare to what RSLogix has for commnenting capabilities.

 

[hd_coop]

I try and comment exactly like you do. I/O name from schematic (PRX123, SOL456, etc) is the symbol name and my comments are also very similar. I also try and put Rung Comments on nearly every line of code. Makes troubleshooting later much easier

 

[OkiePC]

Agree with your use of symbols from schematics. Our I/O are always mapped to internal addresses, so I use the device name as the internal tag symbol, and the wire number as the actual I/O address symbol. (Most of our machines still have old sequential wire numbers leftover from their relay logic days) I have a lot of tags to and from motion controllers and panelviews. All those addresses start out with "TO HMI", or "FROM IMC" followed by the bit description. I edit the comments in a csv file using excel. It's so easy to auto fill the first line of the comments as soon as the address space has been assigned. Then you just import them. In the motion control, I use tag names that refer to the A/B addresses like "I_61_Conveyor_Speed" or "N22_13_Total_Length"...It makes it easier to follow without digging into the block transfers.

 

[msinclair]

I also try and put Rung Comments on nearly every line of code. Makes troubleshooting later much easier

I also date and initial rung comments for changes made after the line was initially commissioned . . .

Marc