Across industrial workshops, mechanical balancing machine beds remain solid for decades while their legacy measurement cards fail, suffer from VFD inverter switching noise, or lose phase lock at low speeds. Engineered by the Rootcastle electronics R&D team, the REI-PRO-04 Unified Controller eliminates separate signal conditioners and external PLCs on a single industrial board.
The board features 3 distinct galvanic isolation domains (24V Field Power 0V_F, Digital Logic GND_L, and ±5V Ultra-Clean Analog Ground AGND_A). Its 4 simultaneous-sampling 24-bit Delta-Sigma ADC channels natively support software-selectable 1 GΩ JFET charge amplification (f_c ≈ 0.015 Hz for piezo force crystals, < 0.7° phase shift at 77 RPM), 4 mA IEPE constant current, and electrodynamic velocity sensors. Combined with 10 Mbps optically isolated tacho/encoder inputs, 8× isolated 24V 0.5A high-side valve/relay outputs, and 2× isolated 0–10V drive outputs, it runs the entire balancing machine.
Benefits
3-domain galvanic isolation (2500–5000 Vrms)
VFD inverter switching transients, contactor spikes and solenoid surges never couple into the precision analog ground (AGND_A).
1 GΩ JFET charge amp + IEPE + Velocity
Directly interfaces high-impedance piezo crystals (pC), industrial IEPE accelerometers, and velocity coils without external boxes.
True 4-channel simultaneous 24-bit sampling
Unlike multiplexed cards, all 4 channels sample on the exact same clock edge with zero inter-channel phase skew.
Rapid 1–2 day legacy machine retrofit
Existing piezo/velocity sensors, tacho/encoders and VFD drives wire directly into terminals X1–X9 for rapid commissioning.
Process
Legacy machine & sensor audit
Inspecting existing piezo/velocity transducers, tacho/encoder signals and VFD motor drive wiring.
REI-PRO-04 panel integration (X1–X9)
Connecting 24V field power (X1), safety & valve I/O (X2–X3), 0–10V VFD drive (X4), encoder/tacho (X5–X6) and 4-ch analog sensors (X7–X8).
REI-Link TCP:1006 & REI-Pool UDP:2222 setup
Commissioning the industrial PC with REI Studio over 100 Mbps isolated Ethernet for real-time FFT and phase-locked vector streaming.
Calibration & operator handover
Verifying influence coefficients and plane separation with calibration masses and issuing an ISO 21940-21 certificate.
Deliverables
- REI-PRO-04 24-bit 4-channel isolated DAQ & controller board
- Complete X1–X9 terminal wiring schematics & cabinet upgrade
- REI Studio bilingual (TR/EN) balancing & metrology software license
- Laser/optical tachometer or incremental encoder (A/B/Z) integration
- Post-retrofit ISO 21940-21 calibration certificate
Applications
- Electronic modernization (retrofit) of horizontal and vertical balancing machines of any make
- High-speed turbocharger VSR balancing rigs (pneumatic valve + NTC + oil pressure + 2 kHz tacho)
- 77 RPM – 3,000 RPM heavy turbine and generator balancing beds
- University and R&D 4-channel phase-locked rotor dynamics test stands
Frequently asked questions
Why use REI-PRO-04 instead of a standard PLC or audio/multiplexed DAQ card?
Standard PLC analog inputs cannot perform synchronous 1X phase-locked demodulation, while generic DAQ cards lack a 0.015 Hz high-impedance (1 GΩ) JFET charge amplifier and 24V industrial galvanic isolation. REI-PRO-04 combines sub-microvolt 24-bit analog metrology with direct 24V industrial solenoid and VFD control.
Why is the 1 GΩ JFET front-end critical for low-speed (77 RPM) balancing?
77 RPM corresponds to a rotational frequency of just 1.283 Hz. A conventional 10 MΩ input stage has a high-pass cutoff around 1.5 Hz, severely attenuating the amplitude and introducing > 40° of phase error at 77 RPM. The REI-PRO-04 charge amplifier uses R_f = 1 GΩ and C_f = 10 nF to place the cutoff at 0.0159 Hz, keeping phase shift below 0.7° at 77 RPM.