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Watch Window enables amplifier and closes servo loop


meindert.norg

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I experienced a weird behavior that I finally was able to explain. Observations: [list] [*]A audible 'click' from the motor every (approx.) 1 second [*]After turning a motor off (#2K), that same motor was enabled within (approx.) 0.5 second (this was what really freaked me out....) [*]I had no PLCs or motion programs running. [/list] Cause: [list] [*]A $7820A entry in a Watch Window [attachment=1422:name] [/list] Background info: [list] [*]Over the past few weeks, while getting to know the Delta Tau controller architecture and software, I added several entries to the Watch Window, never deleting the old entries, unless I needed some space in the window. [*]During my experiments, I apparently entered a memory address ($7820A) instead of the M1002 variable which is the suggested M-variable for this memory address. [/list] Solution: [list] [*]Removed $7820A entry from watch window. [/list] Discussion: [list] [*]I'm not sure what having this entry in the Watch Window does, but it seems as if a pulse of is generated on the controller output, forcing the motor to move slightly. [/list]
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Hi, The problem was caused by the $. The $ commands a motor phase reference search, which depending on the settings of Ixx80, Ixx81 and Ixx91 can be either a search move or a phase reference read based upon lets say hall sensors. Now why does having a '$' in the watch window causes this problem? It's because of the way watch window works. In watch window, every entry gets sent to PMAC and the response for that line is displayed in front of the entry. There is no filter on the type of command that you put into the watch window, you can theoretically put any command in watch window. In your case the "$7820A" was being sent down to PMAC. Here is what I would assume it was doing: $: phase search on the active motor (# will return the active motor number) 7820: a number sent to pmac without any assignment will be assigned to P0 A: abort command for active coordinate system (& will return the active coordinate system) Although not having a filter can cause confusion and headaches once in a while, but it can be useful too. I won't recommend this but you can put commands like P1=P1+1P1 in the watch window, which will increment P1 and display it too! This can be useful during development stage, but make sure to take it out afterwards. Regards,
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