Product Brief
- Model: SPDSI22
- Brand: ABB Hitachi Energy (Bailey Legacy Symphony Plus)
- Series: SPDS series digital input slave I/O module for indoor Harmony DCS control racks
- Core Function: High-density 16-channel isolated digital input board to collect discrete binary field signals: equipment running feedback, circuit breaker position, emergency stop, valve limit, safety interlock and motor status dry contact / 24VDC wet signals. It isolates field side and rack backplane logic circuits, filters industrial EMI noise, converts switch status into digital bus data and transmits to SPBRC series bridge controllers via INFINET backplane bus. Each channel has independent isolation and built-in short-circuit protection to avoid single-channel fault spreading to the whole rack. Conformal coated PCB for humid, coastal and corrosive industrial environments.
- Product Type: Rack-slotted 16-channel isolated digital input slave PCB
- Key Specs: 16 independent digital input channels; supports dry contact or 24VDC sink/source input; 1500VAC galvanic isolation per channel; built-in RC EMI filter; channel-by-channel overcurrent protection; powered via rack backplane 24VDC; Symphony proprietary INFINET bus communication; front POWER / FAIL diagnostic LEDs; ISA G3 anti-corrosion conformal coating; standard Harmony rack slot mounting
- Note: The entire Symphony Plus INFI90 platform is end-of-life. Only remaining factory-new assemblies and fully cyclic-tested surplus boards are supplied as maintenance spares for thermal power, pulp & paper and chemical plant legacy control rooms. Cannot operate standalone; must pair with SPBRC400/SPBRC410 bridge CPU.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | |
| Number of DI Channels | 16 isolated digital inputs |
| Signal Type | Dry contact, 24VDC sink/source |
| Isolation Rating | 1500VAC per channel isolation |
| Input Response Time | Fast scan for safety interlock signals |
| Protection | Channel constant current limiting, short-circuit auto-recovery |
| Backplane Bus | Symphony INFINET proprietary bus |
| Logic Power | 24VDC supplied by rack backplane |
| Front Indicators | Green POWER, Red FAIL |
| PCB Coating | ISA 71.04 conformal anti-salt/moisture coating |
| Operating Temp | -10°C ~ +60°C inside sealed cabinet |
| Humidity | ≤75% RH non-condensing |
| Dimensions | 272mm D × 130mm W × 25mm H |
| Net Weight | 0.74kg |
| Standards | IEC 60282, IEC 62271, CE certified |
Product Introduction
is a high-density digital input slave board widely used in ABB Symphony Plus DCS racks, serving as the signal collection interface between field switches and main bridge controllers. It has three core functions:
- Multi-channel isolated digital signal acquisition16 independent DI channels collect all discrete field status signals. Each channel is separately isolated to eliminate ground loop interference caused by multi-section field equipment. It supports both passive dry contact and active 24VDC transmitter signals without jumper modification.
- EMI filter and continuous self-diagnosisBuilt-in RC absorption filters suppress high-frequency noise from motor starters and variable frequency drives to prevent false signal triggering. The front FAIL LED detects open circuit, short circuit or polarity reversal of any field channel, and uploads fault channel number to SCADA for maintenance alert.
- Transparent bus data transmissionThe board converts on/off status into digital frames and transmits to SPBRC400/SPBRC410 bridge CPU through the INFINET backplane bus. All signal scanning is synchronized with the main controller’s control cycle to ensure real-time safety interlock response.
Conformal coating protects the PCB from salt fog and chemical vapor, making it suitable for coastal power plants and metallurgical workshops. Without a functional , all 16 connected field safety and equipment status signals cannot be monitored by the DCS, forming a safety blind zone.
QA & Testing SOP
- Visual Inspection: Verify part against ABB Symphony spare database; check terminal blocks, PCB coating, gold backplane pins for burn marks, oxidation or cracks; record serial numbers for traceability.
- Full Channel Cyclic Test: Mount on standard Harmony rack test bench, connect 16-channel simulated contact signals, supply 24VDC rack power. Run 24-hour test: signal acquisition accuracy, short-circuit fault trigger, isolation crosstalk check, confirm no false switching under EMI interference.
- Insulation Test: Isolation resistance ≥10MΩ between field terminals and rack ground; chassis continuity <0.5Ω.
- Hardware Record: Photograph terminal wiring layout and rack slot installation steps for field maintenance reference.
- Packaging: Wipe housing with anti-static cloth, cover all terminals with insulating caps, pack into ESD bag + foam carton, attach QC test tag with full 24-hour test log.
Installation Steps & Hazards
Installation Hazards
- Residual 24VDC surge risk: Cut off rack auxiliary power and wait for capacitor discharge before disassembly to avoid signal shock.
- ESD protection required: Anti-static wrist strap mandatory for handling PCB; bare finger contact damages signal chips.
- Polarity reversal risk: Reverse DI field wiring burns input acquisition circuits.
- Do not over-tighten or under-tighten terminal screws; loose wiring causes unstable status reading.
4-Step Replacement Guide
- Preparation: Lock out cabinet 24VDC auxiliary power, wait full capacitor discharge, wear ESD wrist strap, photograph front field terminal wiring and rack slot position of .
- Removal: Disconnect all field DI wires one by one, release front latch, slide out of rack backplane slot.
- Installation: Fix new into original rack slot and lock the latch; rewire all 16-channel field signals strictly following photos, tighten terminals to standard torque.
- Commissioning: Restore rack 24VDC power, green POWER LED lights up; simulate field contact signals to verify correct DI status upload to DCS, trigger single-channel short to test FAIL LED alarm function.
FAQ
Q: Difference between and low-channel DI modules? has 16 isolated channels, high density to save cabinet slots; each channel has independent isolation, while low-density shared-isolation modules suffer severe cross-talk in industrial environments. They cannot be interchanged without recalculating total rack DI channel quantity.
Q: Can work without SPBRC series controller?No. is a passive slave I/O board without data processing capability; it relies entirely on the rack INFINET bus to exchange data with SPBRC400/SPBRC410 bridge CPU.
Q: Can be hot swapped with rack power on?Strictly prohibited. The board connects to live 24VDC backplane bus; live extraction causes signal surge and permanent damage to rack backplane and controller chips. Full auxiliary power lockout is mandatory before replacement.
Q: Warranty policyFactory-new original boards carry 12-month ABB warranty covering all DI channels, isolation circuits and diagnostic LEDs. Tested surplus units have 6-month warranty. Damage from polarity reversal, hot swap or ungrounded ESD voids warranty.
Q: End-of-life statusThe entire Symphony Plus INFI90 platform including is fully EOL. New automation projects adopt 800xA S800 I/O instead; is only for legacy DCS maintenance.
Q: Typical faults of defective Permanent FAIL LED alarm with intact field wiring, random digital input signal loss, severe signal crosstalk between channels, no status change when field contacts switch, overheating under normal load, backplane communication failure without rack damage.
