OMRON Cam Positioner Complete Guide

OMRON 3F88L-160/162 Cam Positioner: A Comprehensive Application Guide from Beginner to Proficient

In the field of industrial automation, cam locators are the core components that achieve precise synchronization between the rotating shaft and the output switch signal. Traditional mechanical camshafts are limited by wear, difficulty in adjustment, and response speed, and have gradually been replaced by electronic cam locators. The OMRON 3F88L-160 (16 point output) and 3F88L-162 (32 point output) series are representative products in this field, with high resolution, high-speed response, and rich compensation functions, making them widely used in packaging machinery, presses, rotating workbenches, and specialized machine tools.

This guide will be based on original factory technical documents and provide a complete operation manual for automation engineers and maintenance technicians, covering hardware selection, functional level configuration, core parameter settings, advanced application skills, and troubleshooting.

Chapter 1: Hardware Overview and Selection Points - Building a Reliable System Foundation

Choosing and installing components correctly before starting any project is the first step in ensuring the long-term stable operation of the system.

1.1 Model and output points

3F88L-160: Provides 16 transistor open collector outputs (maximum 300 mA per point, total current per connector not exceeding 1.6 A), suitable for small and medium-sized control needs.

3F88L-162: Provides 32 outputs, structurally divided into two output connectors (16 points each), suitable for complex devices that require more cam switch signals.

1.2 Selection of Rotary Transformers (Resolvers)

This series uses a rotary transformer as an angle sensor, replacing the vulnerable photoelectric encoder. Provide multiple models to adapt to different installation conditions:

Shaft diameter 10 mm series: standard torque (3F88L-RS17) and high torque (3F88L-RS17T).

Axis diameter 6 mm series: lead out type (3F88L-RS15W) and connector type (3F88L-RS15).

Extension cable: Provides various lengths such as 2 m, 5 m, 10 m, 20 m (such as 3F88L-CR002C, CR005C, CR010C, CR020C), as well as cable components specifically designed for RS15 and RS15W.

1.3 Power and Environmental Requirements

Main power supply: 100~240 VAC, 50/60 Hz, allowable fluctuation range 85~264 VAC. The maximum power consumption is 27 VA.

I/O power supply: 24 VDC (20.4~26.4 V), consumes 145 mA.

Environmental tolerance:

The working temperature is 0-55 ℃, and the storage temperature is -20~75 ℃.

Anti vibration: Complies with JIS C0911, with an amplitude of 0.075 mm at 10~57 Hz and an acceleration of 9.8 m/s ² at 57~150 Hz.

Impact resistance: 147 m/s ².

Insulation and voltage resistance: 20 M Ω or more between the power terminal and the ground terminal (500 VDC megohmmeter); Withstand voltage of 2300 VAC for one minute.

Engineering tip: Before conducting insulation resistance or withstand voltage tests, it is necessary to disconnect the functional grounding terminal from the protective grounding terminal, otherwise it may damage the internal circuit.

1.4 Dimensions and Installation

Dimensions: 110 mm (width) x 100 mm (height) x 82.5 mm (depth).

Weight: Maximum 1 kg.

Installation method: Screw fixation (M4 screws) or DIN rail installation.

Chapter 2: Functional Levels and Basic Operations - Permission Management to Prevent Misoperations

The 3F88L series introduces the concept of Function Level, which can be set through the selection switch on the panel. This is an important design to ensure the safety of on-site operations.

2.1 Detailed explanation of three functional levels

Level names allow operations on typical application scenarios

0 can only monitor the cam output status and current angle, and cannot modify any programs or parameters. During the production and operation phase, prevent operators from mistakenly changing key parameters.

On the basis of level 0, basic operations/monitoring allow the writing of cam programs (i.e. ON/OFF angle data). Daily process adjustments require modifying angles but not system settings.

All functions are open, including initial settings (resolution, rotation direction), compensation parameters (origin, backlash, lead angle), communication settings, etc. When the equipment is first debugged, the rotary transformer is replaced, or the mechanical structure is changed.

Engineering practice: After debugging, be sure to turn the level switch back to 0 or 1 to avoid accidentally modifying key parameters. If it is found that the cam data cannot be modified, first check if the functional level is at 0.

2.2 Panel Operation and Display

The front panel is equipped with 7-segment LED digital tubes, which can cyclically display the current bank, speed, and current angle. Three control inputs (START, TRIG, BANK1~3) and three control outputs (RUN, ERROR, M-DET) provide hard wired interaction capabilities with PLC or upper computer.

START input: It must be set to ON to generate cam output.

BANK input: Select 1-8 banks through 3 binary inputs (8 banks at 360 resolution and 4 banks at 720 resolution). Each bank includes ON/OFF angle settings for all cam outputs.

ERROR output: When the self diagnosis detects a fault, it becomes ON.

M-DET output: Output when the rotation angle matches the set value (commonly used for position arrival indication).

Chapter 3: Initial Settings and Basic Function Configuration - Get the System Moving

After the first power on or replacement of the rotary transformer, two basic initial settings must be completed.

3.1 Encoder Resolution Setting

Can be set to 360 or 720 (per revolution). This setting directly affects:

Angle step size: The minimum unit for 360 resolution is 1 °, and the minimum unit for 720 resolution is 0.5 °.

Maximum response speed: 1600 r/min at 360 resolution and 800 r/min at 720 resolution.

Number of banks: Up to 8 banks at 360 hours and up to 4 banks at 720 hours.

The maximum number of steps for each cam: at 360, the maximum output is 180 steps (one step=one pair of ON/OFF angles), and at 720, the maximum output is 360 steps.

3.2 Rotation direction setting

Set the direction of angle increase (clockwise or counterclockwise) based on the actual mechanical installation direction. This ensures that the panel display angle is consistent with the actual rotation direction, avoiding confusion during debugging.

3.3 Cam Program Writing (Basic Function)

At functional level 1 or 2, the ON and OFF angles can be directly set for each cam output in each bank through the front panel buttons. For example, set output 1 to 45 ° ON, 135 ° OFF, output 2 to 180 ° ON, 270 ° OFF, etc. Data is instantly stored in EEPROM (capable of writing up to 100000 times) without the need for battery maintenance.

Chapter 4: Advanced Application Features - Solving Mechanical and Dynamic Accuracy Problems

Production sites often encounter problems such as angle deviation, mechanical clearance, and high-speed lag. The 3F88L series offers four powerful compensation and adjustment tools.

4.1 Origin Compensation and Origin Shift

Origin compensation: static setting. When the mechanical origin of the rotary transformer does not match the zero degree position required by the equipment, any angle (1-359 ° or 1-719 °) can be defined as the new 0 ° using this parameter. This is a fixed offset.

Origin offset: dynamically triggered. In RUN mode, when the TRIG input signal changes from OFF to ON, the current position is forcibly set to 0 °. This is very useful for reciprocating movements that require automatic calibration of the origin point for each cycle.

4.2 Backlash Compensation

Mechanical transmission chains (such as gears and chains) have forward and reverse clearances, which can cause deviations between the detected angle and the actual load angle. Back clearance compensation allows setting an offset value (1-179 ° or 1-359 °), which is added or subtracted during clockwise and counterclockwise detection to "absorb" mechanical clearance. This is a key parameter for improving the accuracy of positioning repeatability.

4.3 Advance Angle Compensation

This is dynamic compensation for high-speed operation. When the speed increases, due to mechanical inertia and response delay, the cam output often lags behind the actual required position. The lead angle compensation automatically outputs the angle in advance (advance of 1-359 ° or 1-719 °) based on the current speed (1-1600 r/min). For example, in high-speed labeling or cutting applications, this function ensures that the incision accurately lands on the material marking point.

4.4 Teaching Function

Manually rotate the mechanical shaft to a specific position (such as when the material reaches the sensor position), then press the "Teach" button on the panel, and the current rotation transformer angle will be automatically written to the specified cam's ON or OFF angle. This feature greatly simplifies on-site point-to-point work and avoids repeated trial and error.

4.5 Copy Function

On multiple identical devices, a calibrated cam locator can be set as the master station, and all internal cam programs, compensation values, and setting parameters can be copied to other slave station locators at once through a dedicated communication cable (or CompoWay/F communication). This is an efficient method for batch device initialization.

4.6 Testing and Adjustment Operations

Test operation: In PRGM mode, ignore external control inputs (START, BANK, etc.), force cam output, and allow real-time modification of ON/OFF angles. Used for verifying cam angle settings without load.

Adjustment operation: In normal RUN mode, the angle is modified in real-time online, and the cam output immediately changes accordingly. Used for load fine-tuning, it can significantly shorten debugging time.

4.7 Cam Protection

To prevent key cam data from being mistakenly modified, protection levels can be set for each cam or bank. After activation, the protection must be released before modifying the ON/OFF angle.

4.8 One direction Function Settings

Some applications require the cam output to be effective only in forward or reverse rotation (e.g. one-way ratchet mechanism). Through this function, the effective direction can be individually specified for each cam.

4.9 Output Hold Function

When switching from RUN mode to PRGM mode or an error occurs, the cam output will reset by default. After enabling output hold, the output will remain in the state before switching. This can avoid actuator misoperation caused by brief mode switching.

Chapter 5: Communication and Monitoring - Application of CompoWay/F Protocol

The 3F88L is equipped with a serial communication port that complies with the CompoWay/F standard. CompoWay/F is OMRON's unified universal serial protocol, which uses a unified frame format and FINS command structure.

Feasible functions:

Read/write cam programs (batch or single point).

Real time monitoring of current angle and speed.

Read error status.

Remote control start/stop.

Engineering value: Through communication with the upper computer (PLC or industrial control computer), formula management, remote debugging, and production data collection can be achieved without frequent operation of the panel.

Chapter 6: Fault Diagnosis and Daily Maintenance Points

Although the 3F88L series is known for its high reliability, the following issues may still be encountered on-site.

6.1 Camless output

Check if the START input is connected (must be ON).

Check if the functional level is 0? If it is 0, the cam program cannot be run (note: under level 0, the cam output still runs according to the stored program, but cannot be modified; if there is no output, the program may be empty).

Check if the ERROR output is activated? If so, check the panel error code.

Check if the rotary transformer cable is disconnected or has poor contact.

6.2 Unstable or jumping angle display

Possible reason: The rotary transformer is subjected to strong electromagnetic interference. Ensure that the cable uses shielded twisted pair and the shielding layer is grounded at one end.

Check if the mechanical coupling is loose.

6.3 Poor positional repeatability accuracy

Firstly, confirm whether the backlash compensation value is set correctly.

Check if there is excessive wear on the mechanical transmission.

Verify whether the lead angle compensation fails due to changes in speed (such as insufficient compensation range).

6.4 Data saving failure

The EEPROM has a write life of 100000 times. If the cam program is frequently modified through communication or panel, it may approach the upper limit of its lifespan. At this point, the locator should be replaced.

Data loss after power outage? EEPROM is non-volatile and does not require a battery. If it occurs, it may be a hardware malfunction.

6.5 Common Error Tips (Panel Display)

Display (example) meaning processing measures

Check the cable connection for Err1 rotary transformer disconnection or abnormal signal, and measure the coil resistance of the rotary transformer

Err2 EEPROM verification error, rewrite the cam program. If it repeatedly occurs, replace the hardware

Err4 angle setting exceeds the range. Check if the ON/OFF angle is within 0~359 or 0~719

Chapter 7: Precautions for Replacement and Upgrade - Maintenance for Old Equipment

As the original document mentions that the M7F series display unit was discontinued in March 2016, for systems using this display unit, it is recommended to:

Use CompoWay/F communication to replace the display function through the upper computer.

Or upgrade to the new generation of cam locators released by OMRON (compatibility needs to be confirmed).

When the 3F88L body needs to be replaced:

Record all cam programs of the original equipment (read through communication or manually copied).

Record the initial settings (resolution, rotation direction) and all compensation values (origin, backlash, lead angle).

Disconnect the power and replace the hardware.

Reset according to the original parameters and perform a test operation to verify the output logic.

If the copy function is used, the original device can be set as the master station and the new device as the slave station, and all data can be copied with one click.