Omron CJ1W-F159 High-Speed Weighing Unit for CJ-Series PLCs

The Omron CJ1W-F159 is a dedicated load-cell interface unit designed for the SYSMAC CJ-series programmable logic controllers, providing high-precision weighing and force measurement capabilities directly integrated into the PLC system. This weighing unit is manufactured by UNIPULSE and supports up to four 350-ohm load cells in parallel connection. The CJ1W-F159 features a resolution of 1/40000 and a high-speed A/D conversion rate of 500 samples per second, making it suitable for dynamic weighing applications such as checkweighers, filling machines, and batch processing systems.

Key Specifications

• Model: CJ1W-F159 Loadcell Interface Unit

• Product Series: CJ-series Special I/O Unit

• Compatible Busses: SYSMAC CJ1/CJ2 PLC systems

• Number of Load Cell Inputs: 4 (350-ohm load cells in parallel)

• A/D Conversion Speed: 500 samples per second

• Resolution: 1/40000 (approx. 40000 divisions)

• MOSFET Outputs: 2 outputs

• Status Indicators: Front panel LED indicators

• Current Consumption: 300 mA at 5V DC (single 350Ω load cell), 700 mA at 5V DC (four 350Ω load cells)

• Dimensions: 31 × 90 × 65 mm (W × H × D)

• Operating Temperature: 0°C to 55°C

• Storage Temperature: -20°C to 75°C

• Relative Humidity: 10% to 90% (non-condensing)

• Operating Environment: Indoors (no direct sunlight, no corrosive gases)

• Applications: Feed weighing, discharge weighing, hopper scales

High-Precision Weighing Capability

The CJ1W-F159 is engineered for applications requiring accurate weight measurement and control. The unit achieves a resolution of 1/40000, providing precise weight readings from the connected load cells. The use of a high-speed A/D converter operating at 500 samples per second allows the unit to capture rapidly changing weight values, essential for dynamic weighing applications where material is in motion or being dispensed. This combination of high resolution and fast sampling makes the module suitable for checkweighers, filling machines, conveyor scales, and batch process control.

Load Cell Connection and Configuration

The weighing unit supports connection of up to four 350-ohm load cells wired in parallel, enabling the construction of weigh platforms, hopper scales, and conveyor scales with multiple load points. The unit accepts the millivolt-level signals from strain-gauge load cells and converts them to digital weight values for use in the PLC program. The CJ1W-F159 provides excitation voltage for the load cells, eliminating the need for external power supplies. The unit includes onboard filtering and signal conditioning to ensure stable readings in electrically noisy industrial environments.

High-Speed A/D Conversion

The 500 samples per second A/D conversion rate provides the responsiveness required for high-speed weighing operations. In packaging machinery, this speed enables accurate filling control even at high line speeds. In checkweighing applications, the fast sampling allows weight verification of products moving on conveyors without requiring motion compensation algorithms. The high-speed conversion also supports batching operations where rapid weight changes must be tracked precisely to achieve target fill weights within tight tolerances.

PLC Integration and Data Exchange

The CJ1W-F159 integrates with CJ-series PLCs as a Special I/O Unit, exchanging weight data and status information with the CPU through the I/O bus. The PLC can read the current weight value, tare value, and gross weight using standard move instructions. The unit can be configured for various weighing modes including peak hold, valley hold, and sample hold, simplifying programming for common weighing applications. The CPS files enabling the unit to be used in CX-One programming software are available from the manufacturer, ensuring seamless integration into the Omron development environment.

Dual MOSFET Outputs for External Control

The CJ1W-F159 provides two MOSFET outputs that can be used to control external devices based on weight conditions. These outputs can be programmed to activate when weight exceeds setpoint values (over load), falls below minimum values (under load), enters an acceptable range (in tolerance), or reaches pre-set target values. Typical applications include controlling filling valves, activating reject mechanisms, operating sorting gates, and providing status indication to operator panels. The MOSFET outputs provide high-speed switching capability suitable for demanding production environments.

Status Indicators and Diagnostics

Front panel LED indicators provide immediate visual feedback for operational status, simplifying system monitoring and troubleshooting. The diagnostic features allow the PLC program to detect load cell disconnection, A/D converter faults, and communication errors, enabling automated fault handling and operator notification. The unit logs weight readings and can detect abnormal conditions such as unstable weight readings that may indicate mechanical problems or environmental interference.

Weighing Applications

The CJ1W-F159 weighing unit is deployed across a wide range of industrial applications requiring precise weight measurement and control. In feed weighing, the unit controls the rate at which material is introduced into a process. In discharge weighing, it monitors and controls the release of material from bins and hoppers. In hopper scales, it provides inventory monitoring and batch control for bulk material handling. The unit is also suitable for batching systems where precise quantities of multiple ingredients must be combined, and for checkweighers where product weight is verified against specifications.

Environmental and Installation Specifications

The CJ1W-F159 is designed for indoor installation within control cabinets. The unit operates effectively in ambient temperatures from 0°C to 55°C and can be stored at temperatures from -20°C to 75°C. The relative humidity tolerance of 10% to 90% (non-condensing) accommodates typical factory conditions. The compact dimensions of 31 × 90 × 65 mm (W × H × D) allow installation in shallow control cabinets where space is limited. The unit should be mounted away from sources of electrical noise, vibration, and shock to ensure accurate weight measurement.

Conclusion

The Omron CJ1W-F159 high-speed weighing unit provides precision weight measurement for CJ-series PLCs with support for up to 4 load cells, 1:40000 resolution, and 500 samples/sec conversion speed. Its dual MOSFET outputs, indoor environmental ratings, and seamless CX-One integration make it a practical solution for feed weighing, discharge weighing, and hopper scale applications in industrial automation.