Tip of the Day 156: No negatives on stroke scaling, please

“Always with the negative waves, Moriarty…”        ( from…? )

A customer found a way to confuse an eDART™ by entering a negative number in the scaling for the stroke analog input (from the machine). If you are taking injection stroke from the machine instead of the LER-30, always enter a positive number for the stroke full scale like this:

We will probably lock out negative values for stroke on the next release.

The eDART figures out the correct stroke direction using the Screw Run signal and watching the direction of motion^†. It will invert the signal automatically if necessary to get a positive volume and stroke curves. That way we can analyze flow of material from the plastic’s point of view: How much went IN to the mold rather than how much is left in the barrel.

Also, the wiring should be such that the (+) terminal on the analog input always goes above the (-) terminal and not the reverse. The analog input module cannot see negative voltages.

^† If there is no Seq. Module Input / Screw Run going into the eDART then you still need to use positive numbers for full scale. Then set the direction correctly in “Sequence Settings”. The correct direction is that the stroke signal should go positive while the material is being injected into the mold. You also need to set zero at the point just before suckback.