FG4S-600G-90G-NG should be replaced as a preferred nickel-disk FG 4 encoder with a single 15-pole industrial plug, where EncoderWorks can configure a custom compatible replacement solution only if the 600 PPR scaling, S plug pinout, A/B 90° phase relationship, inverted signal pairs, N marker behavior, shielded plug wiring, and coupling preload remain unchanged. The main failure boundary is a machine that runs with visible pulses but calculates the wrong speed, reverses direction logic, or loses zero recovery because the plug mapping, marker input, or phase pair has changed. Typical production lead time: 15 working days.
This configuration belongs to the FG 4 optical incremental encoder platform for heavy-duty industrial environments. It uses 600 pulses per revolution, square-wave output, a 0° basic channel, a second channel electrically shifted by 90°, inverted outputs for industrial signal transmission, and an N marker pulse with inverted marker signal. The S version should be handled as a single 15-pole industrial plug encoder, not as an SS redundant dual-plug unit or a K terminal-box version. Replacement work should focus on plug pin assignment, shield continuity, supply integrity, counter input compatibility, A/B phase sequence, marker interpretation, and mechanical alignment.
System Limits
The first system limit is 600 PPR scaling. A controller configured for 500, 1000, 1024, 1200, or another pulse count may still receive clean A/B signals, but speed, travel, and synchronization values will be wrong. Edge-counting mode, speed conversion, and direction logic should be confirmed before startup.
The second limit is single-plug A/B/N mapping. The 15-pole plug must preserve A, /A, B, /B, N, and /N exactly as expected by the controller. If one inverted signal is omitted, one phase pair is swapped, or the marker input is assigned to a different pin, the machine may run normally but fail during homing, zero recovery, or direction reversal.
The third limit is plug shielding and mechanical preload. The S plug format has a different installation boundary from a terminal box. Plug seating, cable strain, shield bonding, moisture protection, and pin contact condition must be checked. Coupling misalignment, axial preload, radial load, or shaft shock can shorten bearing life and create pulse jitter even when the frequency margin is wide.
Wiring & Installation
Before replacement, record the 15-pole plug pinout for the basic channel, 90° channel, marker pulse, inverted signals, supply voltage, GND, shield connection, LED-check or diagnostic output if used. Confirm that the receiving counter is scaled for 600 PPR and that the machine logic does not rely on a different reference resolution.
During installation, fit the coupling smoothly and do not strike the shaft or housing. Keep the encoder centered, control angular and parallel offset, and avoid axial preload. Route A-/A, B-/B, and N-/N through paired shielded conductors, keep the cable away from inverter output, motor, brake, and contactor wiring, and avoid lateral cable stress at the plug. After commissioning, verify pulse count, speed scaling, direction, N marker repeatability, plug seating, shield continuity, and signal stability through the operating speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed counter and plug interface:
- Match 600 PPR square-wave incremental output with 0°/90° channel behavior and inverted signal pairs
- Preserve S single 15-pole industrial plug structure, N marker behavior, supply range, output level, and controller input compatibility
- Adapt the FG 4 mechanical envelope, shaft interface, flange or foot mounting requirement, coupling alignment, and plug cable layout
- Review 100 kHz / 150 kHz frequency margin, shielded twisted-pair routing, plug pin mapping, bearing load, and marker repeatability
Key Data
| Item | Data |
|---|---|
| Model | FG4S-600G-90G-NG |
| Encoder type | Heavy-duty optical incremental encoder |
| Series | FG 4 |
| Connection structure | S single 15-pole industrial plug |
| Pulses per revolution | 600 PPR |
| Pulse disk class | Preferred nickel-disk pulse rate |
| Signal output | Square wave, 0° and 90° channels |
| Inverted signals | Yes, Option G |
| Marker pulse | Option N with inverted marker signal |
| Plug capacity | Up to 13 outputs |
| Plug protection boundary | IP55 |
| Supply voltage | 12–30 VDC |
| Output type | Differential line driver / push-pull style output |
| Frequency range | 0–100 kHz standard, up to 150 kHz if specified |
| Standard shaft | Ø11j6 × 30 mm |
| Optional shaft | Ø14j6 × 30 mm |
| Key checks | 600 PPR scaling, single 15-pole plug mapping, A/B phase, N marker, plug shielding |
