Configuring Do-More H2-CTRIO2 Multi-Rate Motion Guide

A Do-More processor with an H2-CTRIO2 can execute this 10-inch profile as a short cascade of position-bounded velocity moves. The four travel zones need four constant acceleration rates, not 100 velocity changes at 0.1-inch intervals. Before loading the sequence, resolve one conflict: arriving at 10 inches at 2 in/s and stopping at 10 inches cannot both occur with a smooth, finite deceleration.

Reject the 100-slice quick fix

Updating dynamic velocity every 0.1 inch through CTAXDYNV looks flexible, but it adds calculations, scan-dependent handoffs, and 100 opportunities for rounding or transition error. Coarse velocity steps can also command abrupt changes in pulse frequency. Smaller steps reduce each discontinuity but do not create true constant acceleration automatically.

A stepper axis converts commanded velocity into pulse frequency. A linear frequency ramp produces constant motor acceleration when the mechanics and engineering-unit conversion are linear. Each requested zone already defines its beginning velocity, ending velocity, and distance, so one calculated ramp can cover that entire zone.

Use multiple slices only when deliberately approximating a nonlinear profile, such as jerk-limited transitions, and only after confirming that the controller has no suitable native profile function. They are unnecessary for the four straight acceleration and deceleration lines specified here.

Check whether the endpoints can be smooth

Read actual axis velocity at 0 and 10 inches before choosing the sequence. The stated profile begins at 2 in/s at 0 inches, reaches 2 in/s at 10 inches, and then stops.

No motion instruction can remove velocity instantaneously without an abrupt stop. If the process requires both 2 in/s at exactly 10 inches and zero velocity at exactly the same position, stop and get the process owner to define which condition governs.

Calculate each constant acceleration

Use the distance-domain motion equation v² = u² + 2as, rearranged as . Here, u is entry velocity, v is exit velocity, and s is segment travel. The resulting units are in/s².

The times follow t = (v - u) / a. Under ideal constant acceleration with no entry, stop, or handoff delay, the axis reaches 10 inches after approximately . Use that figure as a diagnostic reference, not as a replacement for position feedback.

Acceleration changes instantly at 3, 5, and 7 inches even though velocity remains continuous. That creates jerk at each boundary. If the liquid process or mechanics cannot tolerate those acceleration corners, define a jerk limit and use a supported smoothing method or a validated finer profile. Do not confuse continuous velocity with continuous acceleration.

Cascade the position-bounded moves

Configure a sequence of CTRUNVEL instructions. Assign the position-reached value for each travel boundary, and use the success bit from one instruction to initiate the next. Confirm the instruction fields and unit scaling in the installed Do-More software and H2-CTRIO2 documentation before commissioning; the project must translate inches and in/s into the axis position and pulse-frequency units correctly.

1. Command the first ramp toward 4 in/s and set its position-reached target to 3 inches.
2. When its success bit becomes true, command the deceleration toward 2 in/s with a target of 5 inches.
3. Use the second success bit to start the ramp toward 4 in/s, ending at 7 inches.
4. Use the third success bit to start the ramp toward 2 in/s, ending at 10 inches.
5. Apply the selected stopping branch: continue beyond 10 inches into a finite stop, or recalculate the final segment so velocity reaches zero at 10 inches.

Interlock each transition so only the intended stage can own the output. Latch the active stage or otherwise prevent a one-scan success indication from being missed. Abort the sequence on a card fault, axis inhibit, unexpected limit input, or failure to reach the commanded boundary.

Commission the resolving branch

1. Verify the home reference and compare indicated position with measured linear travel. A scaling error invalidates every boundary and acceleration calculation.
2. Run at a reduced test condition that preserves the profile structure while remaining inside the machine's operating limits.
3. Trend commanded velocity, actual position, active stage, and each CTRUNVEL success bit.
4. Check that handoffs occur at 3, 5, 7, and 10 inches and that the next instruction starts once per boundary.
5. Compare segment times with 1.000, 0.667, 0.667, and 1.000 seconds. Investigate scaling, load, pulse limits, or transition logic when measured behavior departs materially.
6. Inspect the driven load for lost steps, resonance, coupling slip, and ball-screw backlash. Controller position can look correct while an open-loop stepper has lost mechanical position.
7. Prove the final stopping branch separately, then repeat the complete cycle before returning the dipping process to production.

If a transition bumps, first compare commanded velocity immediately before and after the boundary. Equal boundary velocities point toward acceleration jerk or mechanical response; unequal values point toward profile data, scaling, or stage sequencing. Get it running with the four verified ramps, then document and validate any later smoothing change properly.

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