Component Snapshot At-a-Glance

• Model: DSRF197, full factory part number 3BSE019297R1
• Alt. P/N: DSRF190 (6-slot compact half-size S100 subrack, smaller backplane bus capacity)
• Product Series: ABB S100 I/O, Advant OCS, Advant MasterPiece 200, AC450 legacy DCS platform
• Hardware Type: Full-size metal 12-slot passive I/O subrack chassis, integrated parallel backplane bus, internal 24VDC power distribution busbars
• Key Feature: 12 universal card slots with factory-terminated bus traces, built-in bus impedance termination and distributed rack power rails
• Primary Field Use: House full banks of analog, digital, bus extender and pulse counter I/O modules for remote distributed subracks separated from main controller chassis

Hard-Numbers: Technical Specifications

• Protocol Support: Proprietary parallel system backplane bus, compatible with all series plug-in I/O boards
• Port Count: 12 standard single-width card slots, rear bus extension header for DSBC176 bus extender connection
• Baud/Data Rate: Matches native bus 1 Mbit/s synchronous scan timing synchronized to Advant Master controller
• Operating Temperature: -25°C to +60°C cabinet operational; -40°C to +85°C storage, non-condensing 5–95% RH
• Isolation Rating: Backplane power and signal traces separated by grounded shielding to block cross-slot crosstalk
• Power Draw Capacity: Supports combined module load up to 120W, fed external 24VDC rack power supply via terminal busbar
• Slot Compatibility: All single-width I/O modules (DSAI, DSDI, DSDO, DSDP, DSBC series) fit every slot with no position restrictions
• Bus Termination: Fixed factory bus termination resistors pre-installed on far end backplane to eliminate signal reflection
• Physical Weight: 8.1 kg fully assembled empty chassis, dimensions 283.5 × 418.5 × 238.5 mm
• Certifications: CE, UL/cUL, IEC 61010-1 industrial cabinet safety standard, IP20 cabinet-only rating

The Real-World Problem It Solves

Compact 6-slot DSRF190 half-size racks limit total I/O point density for large MCC and boiler subracks; stacking multiple small racks creates extra bus extension cables and additional cabinet mounting hardware that crowds limited panel space.Custom unpopulated metal frames lack factory-calibrated bus termination. Missing termination resistors create signal reflection noise, triggering intermittent I/O register timeouts and random module fault logs during high-load production shifts.Separate external power distribution terminal blocks add extra wiring junctions prone to loosening from cabinet vibration, introducing voltage drop across dense I/O layouts.Where you’ll typically find it:

• Fossil power plant Advant OCS boiler remote MCC subracks housing temperature RTD, valve AO and breaker DI modules
• Refinery legacy DCS cabinet layouts for reactor and tank farm distributed analog/digital I/O banks
• Pulp mill process line remote I/O cabinets for encoder pulse counters, hydraulic valve solenoid outputs and machine safety contactsThis 12-slot full-size passive subrack consolidates maximum I/O hardware into a single chassis, integrates factory bus termination and built-in power busbars, and eliminates extra cable and terminal hardware for large distributed control layouts.

Hardware Architecture & Under-the-Hood Logic

This is a fully passive backplane chassis with no onboard processing chips; it only distributes 24VDC power and parallel bus signal traces between all installed plug-in I/O modules.

1. External 24VDC power supply connects to dedicated chassis busbar terminals, distributing regulated power evenly to every slot’s backplane power pins.
2. Continuous copper bus signal traces run the full length of the backplane, linking all 12 card slots in parallel synchronous bus topology.
3. Pre-soldered termination resistor network at the far right end of the backplane absorbs bus signal reflections to stabilize waveform integrity on long DSBC176 extended bus runs.
4. Integrated metal shielding partitions between adjacent slots reduce cross-talk interference between high-speed pulse counter boards and low-level analog RTD input modules.
5. Rear edge bus header provides a dedicated tap point for DSBC176 bus extender cables, linking the entire 12-slot subrack back to the main controller master rack.

Field Service Pitfalls: What Rookies Get Wrong

Installing DSRF190 6-Slot Compact Racks To Replace Full-Size Chassis

Junior techs swap half-size subracks without counting total I/O card slots required. Half the planned I/O modules cannot fit, forcing last-minute cabinet rework and incomplete control point commissioning.

• Field Rule: Deploy for layouts requiring 7+ I/O cards; reserve DSRF190 6-slot racks for small auxiliary local I/O groups only.

Removing Factory Pre-Installed Bus Termination Resistors From Backplane

Maintenance staff strip internal termination resistors to test spare boards on bench. Unterminated bus signals develop severe reflection noise, creating constant sporadic I/O dropout faults that do not appear during offline bench testing.

• Quick Fix: Never modify backplane internal resistor networks; use factory DSBC176 bus extender cards for all remote subrack cable runs.

Mixing High-Current DO Solenoid Cards Beside Low-Level RTD Analog Input Cards Without Slot Spacing

Techs pack relay/solid-state DO modules directly adjacent to sensitive DSAI RTD temperature boards without blank filler slots. Inductive switching noise bleeds across backplane traces, generating steady temperature measurement offset drift.

• Field Rule: Separate analog temperature/RTD cards from digital output boards with at least one empty filler slot to reduce backplane cross-talk interference.

Commercial Availability & Pricing Note

Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.