OMP40-2 Optical CNC Probe: Specifications, Modes and Selection Guide
An engineering overview of the Renishaw OMP40-2 optical workpiece probe, including transmission, activation modes, repeatability, environmental limits and the checks required before selecting a compatible replacement.
What is the OMP40-2 used for?
The OMP40-2 is a compact three-dimensional touch-trigger probe for workpiece setup and inspection on small and medium CNC machining centers. It sends probe status optically between the spindle-mounted probe and a machine receiver.
Typical applications include automatic work-offset setting, part alignment, stock allowance checks and in-process feature measurement. A complete installation also requires a compatible receiver or interface, a tool holder, a stylus and CNC probing macros.
Key published specifications
The manufacturer specification describes 360-degree optical transmission in the plane perpendicular to the spindle, with a typical maximum range of 5 m. Published repeatability is 1.0 µm using a 50 mm stylus at a 480 mm/min test speed.
- Sensing directions: ±X, ±Y and +Z
- Unidirectional repeatability: 1.0 µm under the stated test conditions
- Optical transmission: legacy or modulated mode, depending on receiver
- Switch-on: optical command controlled by CNC M-code or auto-start
- Switch-off: optical command or timed shutdown
- Environmental sealing: IPX8; operating temperature: +5 °C to +50 °C
- Power: two 1/2 AA 3.6 V lithium thionyl chloride batteries
Legacy and modulated optical modes
Transmission mode is one of the most important compatibility checks. Legacy mode is associated with older OMI or OMM/MI 12 receiver arrangements. Modulated mode is intended for receivers such as OMI-2, OMI-2T and OMI-2H and provides better resistance to optical interference.
A probe that physically fits the spindle is not automatically compatible. Confirm the receiver model, probe mode, machine control output and existing measurement cycles before ordering a replacement.
Switch-on, switch-off and battery life
The probe can be configured for optical start and optical stop, or optical start followed by a timeout. Published timeout choices are 12, 33 or 134 seconds after the last trigger or reseat event. A longer emergency timeout may apply when a commanded optical stop is not received.
Battery life depends strongly on transmission mode, power setting, duty cycle and battery chemistry. Low optical power can extend service life when the receiver remains close enough throughout the full machine travel.
Installation checks before replacement
Verify line of sight over the entire axis travel, not only at machine home. Coolant residue on either optical window can reduce signal margin, so receiver placement and routine cleaning matter.
- Record the existing probe and receiver model numbers
- Confirm legacy or modulated optical transmission
- Measure tool-holder interface, probe diameter, stylus length and machine envelope
- Check CNC control, available M-code outputs and installed probing macros
- Confirm signal coverage at all expected measurement positions
- Run repeatability and protected-move tests after installation
Frequently Asked Questions
Is an OMP40-2 replacement selected by probe diameter alone?
No. Receiver protocol, transmission mode, shank, stylus, CNC outputs and probing macros must also be compatible.
What is the published OMP40-2 repeatability?
The referenced manufacturer specification states 1.0 µm using a 50 mm stylus at a 480 mm/min test speed.
Can FrontSense review an existing installation?
Yes. Send the probe and receiver models, machine and CNC control, spindle taper, stylus size and installation photographs.