At my first job in this field, the systems integrator at the plant was showing me how to work with Wonderware. Everything mapped to the HMI was comes from just a handful of tags (arrays) that were:
- H_Ind[x]
- H_Alm[x]
- H_Cmd[x]
- etc
So I'm told, if you have to add a button, find the next available H_cmd[x] to address it to. If you need to add an alarm, find the next available H_Alm[x], same as everything else, but for alarms, you must copy/paste H_Alm[x] from the PLC, there is a bug in Wonderware, you can't type H_Alm, it won't accept it.
I says to myself: Self, that doesn't sound right.
So everyone at the plant that has to work on the HMI's does this. copy/paste H_Alm from the PLC.
"Are you sure that your lower case [ell] is not actually an uppercase [eye]?"
It sure was. Ding-dongs named the tag H_AIm thinking that it was H_Alm.
This wonderware instance interfaced with 8 ContorlLogix controllers with with an average of 6 remote 17 slot racks each. The amount of energy that went into that one single typo was laughable. On initial testing, someone scratched their head for a while when none of the alarms would work. Then when they realized that if they copy/pasted the text from the PLC they would work, for some strange reason. So instead of checking the spelling, copy/pasted 500 H_AIm[x] tag names, one at a time. And continued to do it as they commissioned the plant.