BUG - CM 640 - Z value incorrect until first use of BitSetter

[mhotchin (Michael Hotchin)]

On machines with a BitSetter, the Z value is incorrect until the first use of the BitSetter.
To repro:

• Initialize the machine, make sure you are using Workspace (not Machine) co-ordinates.
• Jog Z down and set Z Zero. Precise location not important.
• Jog Z to top of travel. Note Z value.
• Power down, close CM, i.e., behave as if done for the day.
• Power up, initialize.
• Jog Z to top of travel. Note Z value.
• On the ‘Run’ page, do ‘Load new tool’. Don’t actually change the tool, leave as is.
• Now jog Z to top of travel. Note Z value.

Just now, I got the following Z values:

• 66.579
• 4.691
• 66.579

EXPECT - whatever tool offset value was in use at the end of the first CM session should be the starting value for the next CM session. The second value above should be the same as the other two.

With the Z value so far out of whack, people are getting spurious out-of-bounds messages.

Originally discovered here:

[Solved and an FYI] CM 636 and 640 lose Z zero when closed and reopened

Hopefully I didn’t miss something in release notes. Shapeoko 4 XXL with BitSetter. Let’s say I set Z to zero at Machine position -2.000". Machine position says -2.000", Position says 0.000. So far so good. Close CM, open CM, initialize, jog to Machine Position -2.000, Position now says -3.540" instead of 0.000". Happens with v636 and 640. Loaded previous v618 and tried same thing, Z zero stays as I set it. I had reinstalled 640 and ran the new machine wizard with no change.