Constraints in P6

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Dave Scott 👤 Member for 14 years 6 months

I'm semi-new to P6.

I'm trying to hold a date in my schedule.  In the bottom activity box I have the dates selected that I want to hold, but in the schedule the * does not appear.  When I update the schedule, it changes all 100% completed dates to the data date.  If I change the data date, it changes all 100% done activities to that data date.

Any input would be apreciated.

Dave

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Gary Whitehead 👤 Member for 17 years 2 months

From Dave's original post, it sounds like he is trying to "hold" dates which are prior to the data date.

This would not be done by applying a constraint, but by applying actual dates -this is done by ticking the boxes to the left of the started & finished dates

Dave: P6 (correctly) will not allow any activities to have start or finish dates before the data date, unless you have told P6 that the activity has been started or completed, respectively. You do this by ticking the little boxes next to the "start" and "finish" dates.

I think you're proably use to MS Project, which allows for such abhorrences. P6 doesn't.

 

Cheers,

 

G

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Rafael Davila 👤 Member for 22 years 3 months

Mike,

I agree with you.

There is no need to fool CPM math to show criticality under date constraints. If the date constraint break logic then logic dates shall prevail. This is how Spider applies date constraints, shows criticality without breaking logic. A very simple concept, well kind of after you see the dog balls you know is a male dog. It is about correct mathematical modeling.

In Operations Research, a science of British origin similar to Newton Calculus, if you have a Linear Programming problem you have multiple constraints that must be satisfied, the correct solution shall stisfy all constraints. In scheduling you migh have date constraints but you also got logic, and logic is the mother of all constraints. Good scheduling consider all constraints.

Best regards,

Rafael

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Mike Testro 👤 Member for 20 years 6 months

Hi Dave

Why do you want to "Hold" dates in your schedule?

It affects the critical path and causes negative float - all bad planning.

Best regards

Mike Testro

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Anning Sofi 👤 Member for 14 years 4 months

What is the activity type of these activities you want to hold constraint? I suspect they are LOE activities linled to completed tasks.

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Gary Whitehead 👤 Member for 17 years 2 months

Dave,

 

Have you checked the little boxes to the left of the "Started" and "finished" dates on your status tab?

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