CL Varible Assignment Not Retaining Value

04 Jun 2021 04:16 #211125 by jlennox
Hi Guys,

I am having some trouble getting my oiler classic ladder circuitry to work correctly. I have attached a photo of my CL circuit.

Aim: To trigger the oil pump for 10 seconds after every 45 minutes of machine movement. The time on motion must be retained between sessions for consistent oiling.

Explaination: While the machine is in motion (MOVING), the Timer (%TM2) is triggered and times for 1 second. Each time the timer counts it does one of 2 things, it triggers the up pin on the counter and assigns the new counter value to the %W0 variable. The counter (%C0) will count for 2700 seconds (45 minutes) when it will trigger the done output and reset the counter. When the counters done pin rises, it triggers the timer (%TM3) which will turn on my oil pump (OILER) for 10 seconds.

Problem: The circuit itself works as intended and %W0 is updated with the Counter value (%C0.V) as seen in the variables window, however, the Variable Assigment (%W0) is not assigning the counter value (%C0.V) to last assigned value in the previous LCNC session upon start up. It appears to me as if the variable %W0 is not being stored in the internal memory between sessions as per the LCNC documetions for Variable Assingments.

When you assign a value to a variable with the variable assignment block the value is retained until you assign a new value using the
variable assignment block. The last value assigned will be restored when LinuxCNC is started. "

Hypothesies: Perhaps I am misunderstanding the LCNC documention and I need to export and import the Counter Value and store it in the variables .var file using %IWxxx and %QWxxx? Or have i just run into a bug with my installation. It would be appreciated if you classic ladder wizards could shed some light.

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04 Jun 2021 05:01 #211127 by cmorley
Variable values are not recorded at shutdown - I am not sure what the docs were getting at.

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04 Jun 2021 21:52 #211177 by BigJohnT
Probably trying to say in an assignment block the number in there is saved until you change it... dunno who wrote that note... at least I hope it wasn't me.

You would need to store the value in a variable that is 30-5000 and in your .var file.

You can read HAL pins in G code and save that number to a variable, then reverse at the start of your g code to set the counter.


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