×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Term for this "BIT"

Term for this "BIT"

Term for this "BIT"

(OP)
in troubleshooting or debugging on-line i always select a bit to block or disable a rung temporarily until i got my investigation or troubleshooting done...my question is ...is there a universal term for this "BIT" that i can use to communicate with other programmers or technicians?

thanks
dydt

RE: Term for this "BIT"

We like to use the first available bit (b3/0 if it hasn't already been used) and unlatch it unconditionally on the first rung. Use "ALWAYS FALSE" for the description.  When it is stuck on the first rung it is the first thing shown when going on-line.  I have seen other programmers do the same thing using the same description.  Sure this may cause problems if somewhere in the code someone accidently uses it as a coil but if they pay attention to the description it won't happen.  Then when doing some troubleshooting just stick an "always false" bit in.  Anyways it works just fine for us.  

RE: Term for this "BIT"

Depending upon which PLC you're using, there is likely to be such a bit defined in the system. On GE Fanuc PLC's, there is an "ALW_OFF" bit (or conversely an "ALW_ON").

RE: Term for this "BIT"

I have ran across this in programs written by others alot, and it has been refered to as a DUMMY bit and maybe any Bit address.

Works for me

RE: Term for this "BIT"

If you're using something like AB RSLogix you can name your bit and add some pretty lengthy verbage as a description to avoid any confusion. (bitname "SCRATCH_BIT" and description "TOGGLE BIT FOR DEBUGGING 11/12/02" for example).

RE: Term for this "BIT"

"AB" has an "AFI" (Always False Instruction)I just insert it and test edits. Works great and can not be mistakenly toggled high.

RE: Term for this "BIT"

If you were using Direct Logic stuff you would use _off to disable rung. to enable or bypass, you use _on. I hope this
helps. I communicate this to my engineers by saying set False and set True. In symbolic programming everyone would get the idea quite apart from the syntactic mechanism.

We write systems with tybacks, features that may never be utilized in said implementation, and this is how we code them for readability.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources