Installation guide

H-5191-8504-03-B

OMI-2 optical machine interface

© 2015–2022 Renishaw plc. All rights reserved.

This document may not be copied or reproduced in whole or in part, or transferred to any other media
or language, by any means, without the prior written permission of Renishaw.

Renishaw plc. Registered in England and Wales. Company no: 1106260. Registered office: New Mills,
Wotton-under-Edge, Gloucestershire, GL12 8JR, UK.

Compliance information for this product is available by scanning the QR code or visiting
www.renishaw.com/mtpdoc

Renishaw part no: H-5191-8504-03-B

First issued: 02.2015
First revised: 02.2019
Latest revision: 09.2022
Contents

Before you begin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1

Disclaimer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1

Trade marks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1

Changes to equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1

CNC machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2

Care of the interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2

Patents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2

Intended use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2

OMI-2 basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1
Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1
Input voltage ripple. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1

OMI-2 visual diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2

Magnetic label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2
START SIGNAL LED (yellow). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3
LOW BATTERY LED (red). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3
PROBE STATUS LED (green, red). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3
ERROR LED (red, blue, yellow, violet). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3
SIGNAL CONDITION LED (red, yellow, green). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4

OMI-2 inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4

OMI-2 output waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7

Switches SW1 and SW2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8

Switch-on/switch-off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9

OMI-2 dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9

OMI-2 specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.10

 OMI-2 installation guide

System installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1

Mounting bracket (optional). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1

Wiring diagram (with output groupings shown). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2

Contents

Installation with inspection and tool setting probe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

Remote external audible output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

ii OMI-2 cable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4
Cable sealing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4
Fitting flexible conduit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5

Screw torque values Nm (lbf.ft). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1

Cleaning the window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1

Removing the OMI-2 window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2

Fitting the OMI-2 window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3

Fault-finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1
Parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1
Before you begin

1.1

Disclaimer
WHILE CONSIDERABLE EFFORT WAS MADE TO VERIFY THE ACCURACY OF THIS DOCUMENT
AT PUBLICATION, ALL WARRANTIES, CONDITIONS, REPRESENTATIONS AND LIABILITY,
HOWSOEVER ARISING, ARE EXCLUDED TO THE EXTENT PERMITTED BY LAW.

RENISHAW RESERVES THE RIGHT TO MAKE CHANGES TO THIS DOCUMENT AND TO THE
EQUIPMENT, AND/OR SOFTWARE AND THE SPECIFICATION DESCRIBED HEREIN WITHOUT
OBLIGATION TO PROVIDE NOTICE OF SUCH CHANGES.

Trade marks
RENISHAW® and the probe symbol are registered trade marks of Renishaw plc. Renishaw
product names, designations and the mark ‘apply innovation’ are trade marks of Renishaw plc or its
subsidiaries.

Other brand, product or company names are trade marks of their respective owners.

Warranty
Unless you and Renishaw have agreed and signed a separate written agreement, the equipment
and/or software are sold subject to the Renishaw Standard Terms and Conditions supplied with such
equipment and/or software, or available on request from your local Renishaw office.

Renishaw warrants its equipment and software for a limited period (as set out in the Standard Terms
and Conditions), provided that they are installed and used exactly as defined in associated Renishaw
documentation. You should consult these Standard Terms and Conditions to find out the full details of
your warranty.

Equipment and/or software purchased by you from a third-party supplier is subject to separate terms
and conditions supplied with such equipment and/or software. You should contact your third-party
supplier for details.

Changes to equipment
Renishaw reserves the right to change equipment specifications without notice.

CNC machines
CNC machine tools must always be operated by fully trained personnel in accordance with the
manufacturer’s instructions.
 OMI-2 installation guide

Care of the interface

Before you begin

Keep system components clean and treat with care. Do not apply labels to the front of the OMI-2 or
otherwise obstruct the window.

Patents
1.2
None applicable.

Intended use
The OMI-2, which acts as a combined optical transceiver and machine interface, converts signals from
the optical probe into voltage-free solid state relay (SSR) and driven outputs for transmission to the
CNC machine controller.

Safety

Information to the user

In all applications involving the use of machine tools or CMMs, eye protection is recommended.

The OMI-2 has a glass window. Handle with care if broken to avoid injury.

Information to the machine supplier/ installer

It is the machine supplier’s responsibility to ensure that the user is made aware of any hazards
involved in operation, including those mentioned in Renishaw product literature, and to ensure that
adequate guards and safety interlocks are provided.

Under certain circumstances, the probe signal may falsely indicate a probe seated condition. Do not
rely on probe signals to halt the movement of the machine.

Information to the equipment installer

All Renishaw equipment is designed to comply with the relevant EC and FCC regulatory requirements.
It is the responsibility of the equipment installer to ensure that the following guidelines are adhered to,
in order for the product to function in accordance with these regulations:

• any interface MUST be installed in a position away from any potential sources of electrical noise,
i.e. power transformers, servo drives etc;

• all 0 V/ground connections should be connected to the machine “star point” (the “star point” is a
single point return for all equipment ground and screen cables). This is very important and failure to
adhere to this can cause a potential difference between grounds;

• all screens must be connected as outlined in the user instructions;

• cables must not be routed alongside high current sources, i.e. motor power supply cables etc, or be
near high-speed data lines;
• cable lengths should always be kept to a minimum.

Before you begin

• the dc supply to this equipment must be derived from a source which is approved to
BS EN IEC 62368-1.

Equipment operation
If this equipment is used in a manner not specified by the manufacturer, the protection provided by the
equipment may be impaired. 1.3

Optical safety
This product contains LEDs that emit both visible and invisible light.

OMI-2 is ranked Risk Group: Exempt (safe by design).

The product was evaluated and classified using the following standard:

BS EN 62471:2008 The photobiological safety of lamps and lamp systems.

Renishaw recommends that you do not stare at or look directly into any LED device, irrespective of its
risk classification.
 OMI-2 installation guide
Before you begin

1.4

This page is intentionally left blank.

OMI-2 basics

2.1

Introduction
The OMI-2 is a combined optical receiver and machine interface which is designed to be mounted
within the machine’s working envelope.

The OMI-2 operates using a modulated optical transmission mode and is compatible with machine
probes that also operate in modulated mode.

Power supply
The OMI-2 can draw its supply from the CNC machine’s nominal 12 Vdc to 30 Vdc supply.

The maximum supply current is 100 mA when the OMI-2 is transmitting and 40 mA when the OMI-2
is receiving.

The values quoted are based on a 24 Vdc and assume all outputs are open circuit.

CAUTION: This equipment will only perform to specification if the power supply 0 V is connected to
the machine ground (star point).

Input voltage ripple

The input voltage ripple must not cause the voltage to fall below 12 V or rise above 30 V.

OMI-2 visual diagnostics

A visual indication of system status is provided by LEDs. Indication is provided for:

• START SIGNAL;
• LOW BATTERY;
• PROBE STATUS;
• ERROR;
• SIGNAL CONDITION
 OMI-2 installation guide

Magnetic label
A summary of OMI-2 LED activity is provided on a magnetic label. The label may be placed on any
OMI-2 basics

machine flat metal surface.

2.2

PROBE STATUS LED

START LED SIGNAL LED

LOW BATTERY LED ERROR LED

NOTE: Keep the window clean (see Section 4, “Maintenance”).

START SIGNAL LED (yellow)
Lit when a START signal is transmitted to the probe.

OMI-2 basics
This LED will either flash once when a machine control START signal is commanded, or flash at one
second intervals when the system is set to ‘Auto-Start’ mode and is waiting for a probe transmission
signal.

LOW BATTERY LED (red) 2.3

The LED is lit when the activated probe battery voltage falls below a set level.

Replace the probe battery as soon as is practicable after this LED is lit.

PROBE STATUS LED (green, red)

This bicolour LED is lit when the OMI-2 is powered.

Green – Probe is seated.

Red – Probe is triggered or an error has occurred.

The change of colour of this LED will coincide with the probe status output devices changing state.

ERROR LED (red, blue, yellow, violet)

Indicates a transmission error condition,
e.g. optical beam obstructed, probe out of optical range, probe switched off or battery dead.

Red – No communication:
There is no signal from the probe.

Blue – Multiple probe detected:

A second modulated signal is being received.

Yellow – Interference:
Either the signal received from the probe is too weak, or interference is present.

Violet – Good communication:

Interference or a weak probe signal has caused the trigger instant to be delayed.

NOTE: If the ERROR LED is activated because the blue or yellow condition causes the loss of a good
probe signal, or the violet condition occurs, then the indication will persist until the ‘Machine Start’ is
activated or one hour has elapsed.
 OMI-2 installation guide

SIGNAL CONDITION LED (red, yellow, green)

This tricolour LED is lit when the OMI-2 is powered and indicates as follows:
OMI-2 basics

Red – No communication:
There is no signal from the probe.

Yellow – Interference:
2.4 Either the signal received from the probe is too weak, or interference is present.

Green – Good communication:

The condition of signal received from the probe is good.

OMI-2 inputs

Machine start inputs:

Machine start is configurable as a level or pulsed signal.

Level 10 V to 30 V (2.4 mA at 24 V)
When the input is active, the probe is switched on.

Pulsed 12 V to 30 V (10 mA at 24 V)
The probe toggles from being switched on/off. The minimum pulse width is 10 ms.

Machine start wires:

White = positive
Brown = negative

OMI-2 outputs
There are five outputs:

• Probe status 1 (SSR)

• Probe status 2a (5 V isolated driven skip)

• Probe status 2b (driven at power supply voltage)
• Error (SSR)

• Low battery (SSR)

All outputs can be inverted by using switches SW1 and SW2, (see “Switches SW1 and SW2” on
page‑ 2.8).
Probe status 1, Error, Low battery (SSR):

• ‘On’ resistance 50 ohms max.

OMI-2 basics
• Load voltage 40 V max.

• Load current 100 mA max.

Switching times
2.5
• Open to closed 100 µs max.

• Closed to open 25 µs max.

Probe status 2a, (5 V isolated driven skip):

• Load current 50 mA max.

Output voltages

• Sourcing = 4.5 V min at 10 mA.

= 2.4 V min at 50 mA.

• Sinking = 0.4 V max at 10 mA.

= 1.3 V max at 50 mA.

Switching times

• Low to high = 20 µs max.

• High to low = 10 µs max.

Probe status 2b, (driven at power supply voltage):

• Load current = 50 mA max.

Output voltages

• Sourcing (voltage supply – output voltage)

= 2.6 V min at 10 mA.
= 3.5 V min at 50 mA.

• Sinking = 2.0 V max at 10 mA.

= 2.9 V max at 50 mA.

Switching times

• Low to high = 10 µs max.

• High to low = 10 µs max.

 OMI-2 installation guide

CAUTIONS:
OMI-2 basics

Power supply voltage

Do not exceed 30 V between the following:

• the 0 V and the screen wire;

2.6 • the 12 V to 30 V supply wire and screen wire;
• the 12 V to 30 V supply wire and 0 V wires.
The use of in-line fuses at the machine cabinet end is recommended to provide protection for the
OMI‑2 and cable.

Screen connection
A good connection must be made to the machine ground (star point).

Output
Ensure the output from the OMI-2 does not exceed the specified current ratings.
OMI-2 output waveforms

OMI-2 basics
NOTE: Outputs can be inverted by using switches SW1 and SW2 (see “Switches SW1 and SW2” on page 2.8).

Probe
OMI-2 Seated Triggered Seated
Probe Error Probe
SSR/driven Probe Probe Error Low
switch e.g. low switch
outputs on
trigger reseat signal clear battery off
2.7
Power off

Probe status 1
(level)

Normally open
Probe status 1
(pulsed)

Normally open

Error

Normally closed

Probe

OMI-2 Seated Triggered Seated

Probe Error Probe
SSR/driven Probe Probe Error Low
switch e.g. low switch
outputs trigger reseat signal clear battery off
on
Power off

Low
battery

Normally open
Probe status
2a/2b (level)

Normally low

Probe status
2a/2b (pulsed)

Normally low

Signal delays
1. Transmission delay Probe trigger to output change of state = 1.3 ms max.
2. Start delay Time from initiation of start signal to valid signal transmission = 410 ms max.
for kinematic probes and 1 second max. for strain gauge probes.

NOTE: Pulsed outputs are 40 ms ±1 ms duration.

 OMI-2 installation guide

Switches SW1 and SW2

OMI-2 basics

2.8

SW1 SW2

NOTE: To gain access to the switches,

remove the window (see “Removing
the OMI-2 window” in Section 4,
“Maintenance”).

Switch SW1 output configuration Switch SW2 output configuration

PROBE LOW ERROR Rx PROBE MACHINE START START
STATUS 1 BATTERY RANGE STATUS 2a/2B START RANGE

Pulsed N/O N/O N/O 100% Pulsed N/H Level Auto 50%

ON

Level N/C N/C N/C 50% Level N/L Pulsed Machine 100%

Factory settings shown are for: Abbreviations are as follows:

• A-5191-0049 • N/O = Normally Open
• N/C = Normally Closed
• A-5191-0050 • N/H = Normally High
• N/L = Normally Low

CAUTION: Exercise caution when using error or probe SSR in N/O mode as a wiring fault could
cause a loss of error condition and therefore could result in a non-fail safe condition.
Switch-on/switch-off

OMI-2 basics
Switch-on/switch-off method

The OMI-2 operates using either optical on/optical off as the switch-on/switch-off method or auto start.

Optical on/optical off is available with all Renishaw’s OMP range of spindle probes and the optical tool
setter (OTS). Time out, spin on/spin off and shank on/shank off options are also compatible with the
OMI-2. 2.9

Auto start

Auto start selection causes the system to send a start signal at 1 second intervals, and should
only be used when there is no available output from the machine control. In this mode, ensure start
signals cannot be received by probes in the tool changer, on the machine table (e.g. OTS) or on other
machines. Auto start is not recommended for use with the OTS.

Start-up times

In normal operation the start-up time for a modulated probe (as reported by the OMI-2 error signal) is
410 ms max. for kinematic probes and 1 second max. for strain gauge probes.

When turning the probe off and back on, allow 1 second between machine start inputs.

OMI-2 dimensions

84 (3.30) 46.7 (1.84)

40 (1.57) 40 (1.57)
40 (1.57)
45 (1.77)
63 (2.48)

Dimensions given in mm (in) 16 (0.63)

 OMI-2 installation guide

OMI-2 specification
OMI-2 basics

Principal application The OMI-2 processes signals from RENGAGE™ or standard

probes, and converts them into machine outputs, which are
then transmitted to the CNC control.
Transmission type Infrared optical transmission (modulated)
Probes per system One
2.10 Compatible probes OMP40-2, OMP40M, OLP40, OMP60, OMP60M, OMP400,
OMP600 and OTS
Operating range Up to 6 m (19.7 ft)
Weight OMI-2 including 8 m (26.2 ft) of cable = 926 g (32.66 oz)
OMI-2 including 15 m (49.2 ft) of cable = 1457 g (51.39 oz)
Supply voltage 12 Vdc to 30 Vdc (see “Wiring diagram” in Section 3,
“System installation”)
Supply current Transmitting: 100 mA max.
Receiving: 40 mA max.
NOTE: @24 Vdc, all outputs open circuit.
Configurable M-code input Pulsed or level
Output signal Probe status 1, Low battery, Error
Voltage-free solid-state relay (SSR) outputs, configurable
normally open or normally closed.
Probe status 2a
5 V isolated driven output, invertible.
Probe status 2b
Power supply voltage driven output, invertible.
Input/output protection Supply protected by resettable fuse.
Outputs protected by over current protection circuit.
Cable Specification Ø7.5 mm (0.29 in), 13-core screened cable, each core
(to machine 18 × 0.1 mm
control) Length 8 m (26.2 ft), 15 m (49.2 ft)
Diagnostic LEDs Start, low battery, probe status, error and signal condition.
Mounting Flush mounting or directional mounting with optional
mounting bracket (available separately).
Environment IP rating IPX8, BS EN 60529:1992+A2:2013

IK rating IK03, BS EN 62262:2002+A1:2021 [for glass window]

Storage temperature –25 °C to +70 °C (–13 °F to +158 °F)

Operating temperature +5 °C to +55 °C (+41 °F to +131 °F)

System installation

3.1

Mounting bracket (optional)

25 25
(0.98)

19 (0.75)
(0.98)

38 (1.50)
3 holes Ø6.4 (0.25) 3 grip protrusions

100.5 (3.95)
2.0 (0.08)
(1.18)
30
(0.98)
25

3 pairs of holes
Ø5.3 (0.20)
(1.77)
45

permit OMI‑2
mounting in
an alternative
45° orientation
45 (1.77)
2.0
(0.08) 90 (3.54)

Dimensions given in mm (in)

NOTE: Install OMI-2 with cable exiting from lower side for good coolant run off.
 OMI-2 installation guide

Wiring diagram (with output groupings shown)

installation

OMI-2
System

Turquoise
Turquoise/black Probe status 1 (SSR)

3.2 Violet
Violet/black Low battery (SSR)

Green
Error (SSR)
Green/black

White +ve
Brown Machine start input
-ve

5V
Driver Yellow
Signal
Probe status 2a (5 V isolated driven skip)
Grey Return
Driver Orange
Probe status 2b (driven at power supply voltage)
12 V to 30 V Red
0V Black Power supply (12 V to 30 V)

Screen Green/yellow
Machine ground (star point)

CAUTIONS:

The power supply 0 V should be terminated at the machine ground (star point). If a negative supply is
used then the negative output must be fused.

The dc supply to this equipment must be derived from a source which is approved to BS EN IEC 62368-1.
Installation with inspection and tool setting probe
On machines where the OMI-2 is to be integrated with a tool setting probe input, and only one probe
input is provided on the control, an M code can be used to drive an external relay that will select which

installation
probe is monitored.

System
CONTROL RELAY Probe status from OMI-2
3.3
PROBE INPUT
Probe status from tool setter

M CODE

Remote external audible output

Any one of the probe status outputs can be used to drive an external audible indicator when set to
pulsed (see “OMI-2 outputs” on page 2.4).

NOTE: Audible indicator operation is not possible if both skip drives are being monitored by the
control.
 OMI-2 installation guide

OMI-2 cable

Cable termination
installation

A ferrule should be crimped onto each cable wire for a more positive connection at the terminal box.
System

Standard cable variants

3.4
The OMI-2 standard polyurethane cables are 8 m (26 ft) and 15 m (49.2 ft) long.

Please contact Renishaw for other cable lengths.

Cable specification

Ø7.5 mm (0.29 in), 13 core screened cable, each core 18 × 0.1 mm.

Cable sealing
Coolant and dirt are prevented from entering the OMI-2 by the cable sealing gland. The OMI-2 cable
can be protected against physical damage by fitting a flexible conduit if required.

A recommended flexible conduit is Anamet™ Sealtite HFX (5/16 in) polyurethane.

A conduit kit is available (see Section 6, “Parts list”).

CAUTIONS:

Failure to adequately protect the cable can result in system failure due to either cable damage or
coolant ingress through cores into the OMI-2.

Failure due to inadequate cable protection will invalidate the warranty.

When tightening or loosening nut B on the conduit, ensure that torque is only applied between A and
B.
Fitting flexible conduit

installation
System
3.5

Adaptor A

Conduit
termination
piece

Cable
Plastic olive

Flexible
Nut B
conduit

NOTE: Conduit bulkhead fittings require a clearance hole for an M16 thread.

1. Slide nut B and the plastic olive onto the conduit.

2. Screw the conduit termination piece into the end of the conduit.

3. Fit the conduit to adaptor A and tighten nut B.

 OMI-2 installation guide

Screw torque values Nm (lbf.ft)

installation
System

×2
3.6

3.0 mm A/F
2 Nm
(1.47 lbf. ft)
×2

8.0 mm A/F 4.0 mm A/F

5 Nm
(3.68 lbf. ft)
m A/F
19.0 m

HOLD

22.0 mm (7/8 in A/F)

22 Nm (16.22 lbf. ft)
MAXIMUM
Maintenance

4.1

Maintenance
You may undertake the maintenance routines described in these instructions.

Further dismantling and repair of Renishaw equipment is a highly specialised operation, which must
be carried out at an authorised Renishaw Service Centre.

Equipment requiring repair, overhaul or attention under warranty should be returned to your supplier.

Cleaning the window

Wipe the window with a clean cloth to remove machining residue. This should be done on a regular
basis to maintain optimum transmission.

CAUTION: The OMI-2 has a glass window, handle with care if broken to avoid injury.
 OMI-2 installation guide

Removing the OMI-2 window

It is not necessary to remove the OMI-2 from the machine when adjusting the switch or installing
Maintenance

replacement parts.

The window may be removed and replaced as described below to change the switch settings.

To remove the OMI-2 window

4.2

A
B

B
A

CAUTION: DO NOT remove the window by twisting or rotating.

1. Clean the OMI-2 to ensure no debris enters the unit.

2. Remove the four cover screws, using a 2.5 mm A/F hexagon key. Two screws are short and two
are long. Two of the cover holes are threaded A, and two are plain B.

3. The window fits tightly on the OMI-2 body, and is removed using the two long screws, which are
inserted into the threaded holes A.

Tighten each screw a few turns at a time to pull the window up evenly. When it is clear of the body,
remove the window and screws completely.
Fitting the OMI-2 window
1. Before fitting the window, check for any damage to screws or scratch marks which could prevent

Maintenance
sealing.

2. Ensure the O-ring seating A in the OMI-2 body is clean.

3. Ensure that the O-ring B and window C are clean.

4.3
A

4. Insert the two short screws into window holes D, and tighten.

5. Place the window complete with the O-ring onto the OMI-2 body.

M3 screws (D)
2.5 mm A/F × 2
0.3 to 0.5 Nm (0.22 to
D 0.37 lbf.ft)
E

E
D M3 screws (E)
2.5 mm A/F × 2
0.9 to 1.1 Nm (0.66 to
0.81 lbf.ft)

NOTE: The O-ring should be lightly lubricated with grease.

6. Insert the long screws into holes E. and tighten each screw a few turns at a time, to pull the
window down evenly. There may be some resistance due to some compression of air trapped
inside the body.
 OMI-2 installation guide
Maintenance

4.4

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Fault-finding

5.1

Symptom Cause Action

The probe fails to switch Installation / CNC program fault. Correct the M–code wiring and/or
on when in Optical Start the CNC program.
mode or fails to switch
off when in Optical Stop The probe is out of the start Change the CNC program to bring
mode. range. the probe within the start range
of the OMI-2 and ensure that the
appropriate start range is selected.

The transmission beam is Clean the OMI-2 window and

obstructed. remove any obstructions.

Incompatible probe / probe Change the probe or probe setting

transmission setting. to modulated PROBE1.

Incorrect Machine Start setting. Reconfigure the Machine Start

setting SW2.

Dead probe batteries. Replace the probe batteries.

Optical interference is blocking Check the OMI-2 visual

the start signal. diagnostics. For instructions
describing how to check the visual
diagnostics (see “OMI-2 visual
diagnostics” on page 2.2).
Remove the source of interference
or reposition the OMI-2 such that
interfering light does not shine
onto the OMI-2 window or probe
window.
 OMI-2 installation guide

Symptom Cause Action

The probe stops in The transmission beam is Remove the obstruction.

Fault-finding

mid-cycle. obstructed.
or
An unexpected error Optical interference. Remove the source of interference
occurs during a or reposition the OMI-2 such that
5.2 probing cycle. interfering light does not shine into
or the OMI-2 window.
An unexpected trigger
Intermittent wiring fault. Correct wiring.
occurs during the
probing cycle. The probe has moved outside the Change the CNC program to bring
reception range. the probe within the reception
range of the OMI-2 and ensure
that the appropriate reception
range is selected.

The probe is in Timer Off mode Increase the Timer Off time setting
and has not been triggered for the or change the probing routine.
timer period.

The probe has not been triggered Restart the probe and ensure
for more than 90 minutes. that the probe is not idle for
90 minutes.

The probe switches on, Interfering light source is shining Check the OMI-2 visual
but the OMI-2 error LED directly into the OMI-2 window. diagnostics. For instructions
remains lit. describing how to check the visual
diagnostics (see “OMI-2 visual
diagnostics” on page 2.2).

Remove the source of interference

or reposition the OMI-2 such that
the interfering light does not shine
into the OMI-2 window.

The probe is out of range. Check the signal condition LED.

Change the CNC program to
move the probe into the reception
range of the OMI-2 and ensure
the appropriate reception range is
selected.

The probe is triggered when Reseat the probe.

OMI‑2 is set to Level Machine
Start.

A signal is being received from Change the adjacent probe to low

a probe on an adjacent machine power mode or change the OMI‑2
tool. reception range to 50%, if this
range is acceptable.

Installation / CNC program fault. Check wiring and CNC program.

 Symptom Cause Action

The probe indicates Installation / CNC program fault. Correct low battery SSR wiring

Fault-finding
low battery condition, and/or CNC program.
but the machine control
does not.

The machine control Probe is not switched on. Attempt to switch it on. 5.3
does not respond to the
probe being triggered or Probe is out of range. Change the CNC program to bring
seated. the probe within the reception
range.

Installation / CNC program fault. Correct the probe status output(s)

wiring and CNC program.

A signal is being received from Change the adjacent probe to low

a probe on an adjacent machine power mode or change the OMI-2
tool. reception range to 50%, if this
range is acceptable.

Probe triggers but the The OMP400 or OMP600 has Reconfigure the OMP400 or
OMI-2 does not respond. the 3 second switch-on mode OMP600 to the standard switch-
selected. on delay.

The probe is out of range. Review the performance

envelopes.

The transmission beam Check that the probe and OMI-2

obstructed. windows are clean, and remove
any obstruction.

The probe is set to legacy Reconfigure to modulated

transmission. transmission.

Low battery, Probe An output overload has occurred. Remove power to the system and
status and Error LEDs remove the source of the problem
are flashing red. Turning on the system will reset
the OMI-2.
If the system displays any other
symptom, check the installation
before contacting your local
Renishaw office.
 OMI-2 installation guide
Fault-finding

5.4

This page is intentionally left blank.

Parts list

6.1

Item Part number Description

OMI-2 A-5191-0049 OMI-2 with 8 m (26 ft) cable, magnetic label, tools and
product support card.
OMI-2 A-5191-0050 OMI-2 with 15 m (49 ft) cable, magnetic label, tools and
product support card.
Mounting bracket A-2033-0830 Mounting bracket.
Conduit A-4113-0306 Conduit kit with 1 m (3.28 ft) of polyurethane conduit and
bulkhead connector (M16 thread).
Window A-5191-0019 Comprising: window assembly with O-ring,
replacement 3 × stainless steel M3 × 14 mm long screws,
3 × stainless steel M3 × 5 mm long screws and
1 × 2.5 mm hexagon wrench.
Tools A-5191-0300 Comprising: 1 × 2.5 mm hexagon wrench, 1 × 4 mm hexagon
wrench, 14 × ferrules, 2 × M5 screws, 2 × M5 washers and
2 × M5 nuts.
Publications. These can be downloaded from our website at www.renishaw.com.
OMP40-2 H-4071-8504 Installation guide: for the set up of the OMP40-2
OLP40 H-5625-8504 Installation guide: for the set up of the OLP40
OMP400 H-5069-8504 Installation guide: for the set up of the OMP400
OMP60 H-4038-8505 Installation guide: for the set up of the OMP60
OMP600 H-5180-8504 Installation guide: for the set up of the OMP600
OTS H-5401-8504 Installation guide: for the set up of the OTS

NOTE: The serial number of each OMI-2 unit is found at the bottom of the housing.
Renishaw plc T +44 (0)1453 524524
New Mills, Wotton-under-Edge F +44 (0)1453 524901
Gloucestershire, GL12 8JR E uk@renishaw.com
United Kingdom www.renishaw.com

For worldwide contact details, visit

www.renishaw.com/contact

© 2015–2022 Renishaw plc Issued: 09.2022 Part no. H-5191-8504-03-B