Configuring Mitsubishi Simple Motion Modules (RD77MS & FX5-40SSC) in GX Works3: Multi-Axis Positioning Tables
1. Simple Motion Optical Architecture vs Legacy Pulse Trains
Controlling multi-axis systems (Cartesian robots, gantry pick-and-place, packaging machines) via traditional pulse trains demands massive conductor looms vulnerable to EMI interference. Mitsubishi Simple Motion Modules (iQ-R RD77MS and iQ-F FX5-40SSC-S / FX5-80SSC-S) deploy SSCNET III/H 150 Mbps optical buses: - Immunity to Noise: Daisy-chains MR-J4-B or MR-J5-B servo drives using fiber optic cords, delivering zero electromagnetic interference. - Microsecond Synchronization: Bus update cycles run down to 0.222 ms to 0.888 ms, enabling synchronized 2-axis circular interpolation, electronic line-shafting, and dynamic Electronic Camming (E-CAM).
2. GX Works3 System Configuration Workflow
- In GX Works3, navigate to Navigation -> Parameter -> Module Information and insert the target Simple Motion module (e.g. FX5-40SSC-S).
- Double-click Simple Motion Setting Tool to launch the specialized motion parameter editor.
- Under System Configuration, assign connected drive models per axis channel (e.g. Axis 1 = MR-J4-B).
- Under Basic Parameters, define engineering units (`μm`, `mm`, `degree`, or `pulse`), lead screw pitch per revolution, and encoder gear ratios.
3. Positioning Data Table Architecture
| Table Column | Parameter Type | Command Options | Functional Meaning |
|---|---|---|---|
| Operation Pattern | Continuity Flag | 0: Complete, 1: Continuous, 2: Continuous Path | Specifies whether axis halts at coordinate or seamlessly blends into next step without stopping. |
| Control System | Kinematic Mode | 1-Axis Linear ABS/INC, 2-Axis Circular Interpolation | Selects linear or multi-axis coordinated circular arc trajectory. |
| Command Speed | Velocity Reference | e.g. 50,000 mm/min | Programmed cruising traverse velocity for current trajectory segment. |
| Positioning Address | Target Coordinate | e.g. 120.500 mm | Target position in absolute coordinates or relative increment. |
| Dwell Time | Settle Delay | e.g. 100 ms | Settling delay elapsed before confirming In-position arrival. |
4. Executing Positioning Start Commands in Ladder Logic
// Initiating Axis 1 Positioning Execution via Data Table Point 1
// Uses Simple Motion Buffer Memory structures in GX Works3
// 1. Verify drive ready and write target Point No. 1 into buffer memory
[ M0 ] --- [ AND U0\G6000.0 ] ----------------- [ MOV K1 U0\G1500 ]
// (Loads Point 1 into Axis 1 Positioning Start Number)
// 2. Assert hardware positioning start command bit
[ M0 ] ---------------------------------------- [ SET U0\G6002.0 ]
// 3. Acknowledge motion initiation: Reset command bit once Axis Busy is asserted
[ U0\G6001.0 ] -------------------------------- [ RST U0\G6002.0 ]Mandatory Software Stroke Limit Configuration
Always configure Software Stroke Limit Upper/Lower boundaries under Detailed Parameters. If an operator keys an erroneous HMI coordinate, the Simple Motion ASIC intercepts the command before acceleration, preventing catastrophic mechanical crashes.