Focus Axis Pulls Back to Infinity — Damaged UltiBox Port¶

Summary¶

If Focus is stuck at infinity and pulls itself back to infinity whenever the focus axis is enabled, test a different UltiBox port. In the resolved case, moving Focus from Network 1 Port 5 to Network 1 Port 6, using the Zoom port, restored control. Simon Wakley noted this points to a damaged encoder reader or amplifier on Port 5.

Symptoms¶

Focus axis cannot be moved because it is stuck on infinity.
Manually rolling focus toward close focus works mechanically, but enabling the axis pulls it back to infinity.
Reverse motor direction does not help.
Problem occurs in Independent and FFO modes.
Opening another lens profile shows the same behaviour.

Community Solution¶

[CONFIRMED] Move the Focus axis to a known-good UltiBox port¶

2025-05-15 — Michael deAnthony / MRMC Support / Simon Wakley

Open Setups -> Axis Setup, select the Focus axis, and check the axis network / port assignment.
In the reported case: change Focus Network 1 Port 5 to Network 1 Port 6.
Use Setups -> Network Setup to confirm the UltiBox and available ports are visible, then use the Zoom port temporarily if required.
Test focus from limit to limit.
If Port 5 repeats the fault, mark it for MRMC repair; the UltiBox still has other usable ports.

confidence_score: 0.9

Important Clarification¶

The attached error referenced EtherCAT, but MRMC Support clarified that EtherCAT is the Staubli arm, not the lens motor. The focus symptom was resolved by changing UltiBox port, not by EtherCAT troubleshooting.

Image description: attached error referenced EtherCAT, but the resolved lens fault was a focus axis that pulled back to infinity because the UltiBox focus port was damaged. Searchable terms: EtherCAT; Focus Network 1 Port 5; Network 1 Port 6; focus stuck at infinity; focus pulls back to infinity.

Media Text / Description¶

Image description: attached error referenced EtherCAT, but the resolved lens fault was a focus axis that pulled back to infinity because the UltiBox focus port was damaged.

Media 1: Image description: attached error referenced EtherCAT, but the resolved lens fault was a focus axis that pulled back to infinity because the UltiBox focus port was damaged. Searchable terms: EtherCAT; Focus Network 1 Port 5; Network 1 Port 6; focus stuck at infinity; focus pulls back to infinity.