Product Core Brief

• Model: F3SP21-0N
• Brand: YOKOGAWA
• Series: FA-M3 Range-free Controller
• Core Function: Sequence CPU module for FA-M3 PLC systems, executing ladder logic programs and managing rack I/O scanning.
• Product Type: Sequence CPU Module
• Key Specs: 10,000-step ladder capacity | 350 mA @ 5 V DC current consumption | Supports FA-M3 I/O and special function modules
• Condition: New Original / New Surplus

Key Technical Specifications

• Product type: Sequence CPU module for FA-M3 PLC
• Series compatibility: FA-M3 range-free controller
• Program capacity: 10,000 steps (ladder logic)
• Current consumption: 350 mA at 5 V DC (backplane bus)
• External power supply: None required from field side; powered via backplane
• Communication interface: Supports serial connection for programming and monitoring
• Compatible base modules: FA-M3 4/5/6/9/13/16-slot base units
• System expansion: Supports up to 7 sub-units via fiber-optic FA-bus (with F3LR02 interface)
• Max I/O points: Up to 8,192 range-free I/O points across the system
• Mounting: FA-M3 base module slot (slot 001 in main rack)
• Handling: ESD-sensitive industrial control module

 

Product Introduction

The F3SP21-0N is a sequence CPU module for the YOKOGAWA FA-M3 range-free PLC platform. It executes ladder logic programs with a 10,000-step capacity and serves as the central processor for the rack, scanning I/O modules and managing system communication.

This is an entry-level CPU in the FA-M3 lineup, commonly found in legacy machine control and small process skid applications. For maintenance teams, it is a critical spare because CPU failure means a complete station outage. Having a verified replacement on hand avoids extended downtime while waiting for hard-to-source legacy parts.

 

QA & Testing SOP

CPU modules are the most sensitive components in the rack. Each unit is handled with care:

1. Visual and label inspection: Confirm the model plate reads F3SP21-0N and check for housing damage, connector wear, or signs of overheating.
2. Backplane connector check: Pins are inspected for bending, oxidation, or contamination that could cause poor contact in the base slot.
3. Power-up test: The module is seated in a compatible FA-M3 base and energized to confirm normal startup and LED status.
4. CPU recognition test: The module is verified to be recognized by the rack and to respond to programming software communication.
5. Memory integrity check: Program memory is checked for corruption or read errors.
6. ESD-safe packaging: Units are packed in anti-static materials with connector protection for shipment.

Note: Full functional validation requires loading an existing program and running I/O scans. If a site-specific loop test is required, confirm the program backup and I/O configuration before dispatch.

Installation Pitfalls & Guide

❗ Slot 001 is reserved for the main CPU. In the main rack, the F3SP21-0N must be installed in slot 001 (immediately to the right of the power supply section). Placing it in the wrong slot will prevent the system from booting.

❗ Back up the program before removing the old CPU. If the failed CPU still has readable memory, download the program first. If memory is lost, you will need the original program backup from your engineering station.

❗ Do not mix CPU models without verifying compatibility. The F3SP21-0N is a 10K-step CPU. Replacing it with a higher-capacity model (e.g., F3SP25-2N, F3SP35-5N) may work mechanically but requires confirming program compatibility and firmware support.

❗ Handle the module by the edges. The backplane connector and front panel are sensitive to ESD and mechanical stress. Use a grounded wrist strap during installation.

Replacement steps:

1. Pre-install: Back up the CPU program, record slot assignments, and note any ROM pack or memory card installed.
2. Removal: De-energize the rack, remove any memory card or ROM pack, and pull the CPU straight out of slot 001.
3. Install: Seat the replacement CPU firmly in slot 001, reinstall the memory card/ROM pack if applicable, and secure the locking mechanism.
4. Power-on test: Restore power, verify CPU RUN/STOP status, check for fault LEDs, and confirm I/O scanning without errors.

 

Technical FAQ

Is the F3SP21-0N a direct replacement for my existing FA-M3 CPU?
Yes, if your current CPU is also an F3SP21-0N. The module is a standard FA-M3 sequence CPU and fits any FA-M3 base slot. Program and I/O configuration can be retained if the memory is intact or restored from backup.

Can I upgrade from F3SP21-0N to a higher-capacity CPU?
Potentially yes. Higher-capacity CPUs like F3SP25-2N or F3SP35-5N are pin-compatible, but you must verify program compatibility, memory requirements, and firmware support before swapping. Always consult the FA-M3 hardware manual for your specific configuration.

What happens if the CPU loses its program memory?
The F3SP21-0N relies on internal memory or an optional ROM pack (e.g., RK10-0N for 5K steps, RK30-0N for 20K steps). If memory is lost and no backup exists, the program must be re-downloaded from the engineering workstation.

Is this module still available as new stock?
The FA-M3 platform is a mature product line. New-original and surplus stock are commonly available through industrial spare channels, but availability varies by region. Confirm stock condition and warranty terms before ordering.

Do you offer warranty on surplus units?
Surplus and new-original modules are typically covered by a limited functional warranty. Exact terms depend on stock source, so confirm warranty length and return conditions before purchase.