Description
The Honeywell 8C-TPOX01 (part number 51307022-175) is the G3 conformal-coated, non-redundant, 32-channel 24 V DC digital output IOTA (Input/Output Termination Assembly) for the Honeywell Experion PKS Series 8 I/O system. It mates with the 8C-PDOX01 32-channel digital output IOM (Input Output Module) and turns C300 controller bits into 32 galvanically isolated, fused, short-circuit-protected, LED-indicated 24 V DC switch contacts that drive solenoid valves, motor starters, alarm horns, indicator lamps and relay coils.
It is not a processor, not a gateway and not a communication card—despite the confused listings that persist online. The 8C-TPOX01 is the termination half of a two-part system: the IOTA owns the screw terminals, the 250 Ω sense resistors, the fusing, the optical isolation and the conformal coating; the 8C-PDOX01 IOM owns the logic, the diagnostics and the I/O Link protocol. Understanding that split is the difference between a fifteen-minute repair and a misdiagnosed weekend outage.
Application Scenarios
A Gulf Coast ethylene cracker runs a 4,200-point Experion PKS system across seven process units. The digital-output count alone is 1,180 points: block-valve solenoids, pump-start permissives, steam-turbine trip solenoids, alarm horns, stack-light segments and a long tail of “energize to trip” interlocks. The original I/O design used 16-channel discrete DO cards at roughly double the panel width. The cabinet farm had physically run out of rail, and the marshalling room was slated for a $140,000 expansion.
The instrument team regrouped the points by function and by fault domain, then consolidated onto the Honeywell 8C-TPOX01. At 32 points per IOTA in a single Series 8 slot, the DO module count fell by roughly half, the planned cabinet addition was cancelled, and the wire count stayed the same because the IOTA termination density is what changed—not the field wiring. The engineering discipline that made it work was deliberate: safety interlocks and “energize-to-trip” paths were separated from ordinary on/off commands, and the fail-safe state of every channel was re-validated in the control strategy. The result was 0.36 kg of PCB doing the job that would have required another square metre of panel. Eighteen months later, with trace H₂S and salt fog in the cabinet atmosphere, the G3-coated IOTAs showed no conformal degradation, and I/O-related process upsets were zero.
The same part solves a different problem in a North Sea platform’s produced-water skid. Here the hazard was not space but transients. A 75 kW inducer motor, two VFDs and a 400 V busbar lived in the same E-house. Every grounded contactor close pushed a common-mode spike down the solenoid cable and into the DO card, nuisance-tripping the skid. The 8C-TPOX01‘s 2500 V DC system-to-field isolation broke the path. The spike dissipated in the field device, not in the C300 backplane. The “DO card failed” work order, which had averaged 11 per year, disappeared. The fix cost less than the investigation had.
Parameter
| Main Parameters | Value / Description |
|---|---|
| Product Model | 8C-TPOX01 |
| Part Number | 51307022-175 (“8C” = G3 conformal coated; uncoated alternate is the 8U-TPOX01, P/N 51307022-275) |
| Associated IOM | 8C-PDOX01 — 32-channel 24 V DC digital output IOM (the logic/driver card) |
| Manufacturer | Honeywell Process Solutions, USA |
| Product Category | Digital output IOTA (Input/Output Termination Assembly) — field-wiring termination board, not a processor |
| Platform | Honeywell Experion PKS / Experion LX, Series 8 I/O, C300 controller, PlantCruise |
| Configuration | Non-redundant (redundant equivalent: 8C-TPOX02) |
| Output Channels | 32 channels, single-ended, grouped |
| Output Type | 24 V DC sourcing (PNP) digital output |
| On-State Voltage | 22 … 30 V DC (L+ referenced) |
| Output Current | 500 mA per channel, 32 channels simultaneously active |
| Surge Current | 5 A for 10 ms (inrush, e.g. contactor / relay coil) |
| Load Inductance | ≤ 1.2 H |
| Leakage Current (off state) | Max. 0.5 mA |
| Voltage Drop (on state) | Max. 0.8 V |
| Power Dissipation (worst case) | 9.6 W (32 channels × 500 mA × 0.6 V) |
| Overload / Short-Circuit Protection | Yes — per channel, with electronic shutdown and automatic retry |
| Open-Circuit Detection | Yes — detects load-side open circuit |
| Watchdog | Configurable hardware watchdog: off, 1 s, 10 s |
| Status Indication | 2 LEDs per channel (command / feedback) + module OK LED + I/O Link status |
| Diagnostic Coverage | Channel short, overload, open circuit, group fault, module OK, I/O Link and backplane health reported to DCS |
| Electrical Isolation | 2500 V DC system-to-field galvanic isolation; optical isolation on the serial/backplane interface |
| Signal Conditioning | Integrated 250 Ω precision sense resistor per channel for feedback verification |
| Fusing | Per-group replaceable fuse on the IOTA (fuse rating per Honeywell SBOM; keep spares) |
| Supply Voltage | Backplane 24 V DC (18 … 32 V DC), drawn from the Series 8 carrier |
| Current Consumption | ≈ 120 mA typical @ 24 V DC (module logic); load current is field-supplied via L+ |
| Failure-Safe Behavior | Configurable per channel: hold last state, or drive to user-defined safe state on module/link fault |
| Hot Swap | RIUP — Removal and Insertion Under Power supported |
| Redundancy | Redundant I/O Link and redundant C300 supported; the IOTA itself is non-redundant |
| Terminal Type | Screw-compression field terminals on the IOTA faceplate |
| Physical Size | 6-inch IOTA (non-redundant, pairs with 9-inch 8C-PDOX01 IOM) |
| Dimensions (L × W × H) | ≈ 293 × 120 × 65 mm (IOTA PWA) |
| Weight | ≈ 0.36 kg |
| Protection Class | IP20 (cabinet installation) |
| Mounting | Vertically on Series 8 I/O rack / carrier base; EMC faceplate screws must be torqued |
| Operating Temperature | –40 … +70 °C (G3-coated 8C variant) |
| Storage Temperature | –55 … +85 °C |
| Relative Humidity | 5 … 95% RH, non-condensing |
| Environmental | G3 anti-corrosion conformal coating per ANSI/ISA-S71.04 (mixed-gas, salt-fog, high-humidity) |
| EMC | EN 61000-6-1 / -6-2 / -6-3; surge protection EN 61000-4-5 (1 kV line-to-line, 2 kV line-to-ground for industrial locations) |
| Agency Approvals | CE, UL, CSA, TÜV; Class I Division 2, Groups A/B/C/D, T4; Class I Zone 2, Ex nA IIC T4; ATEX Zone 2; RoHS |
| Safety | SIL-capable in the applicable Series 8 architecture (IEC 61508); final SIL claim is system-level |
| Lifecycle Status | Active /常规备件供货 (mature platform; source as new-surplus or decommissioned-plant material for older revisions) |
