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The 8C‑TDOBA1 is a digital output I/O module (often called DO IOM / DO IOTA / DO termination assembly) in the Series 8 (S8) family. It is designed for use in distributed control systems (DCS) or process automation architectures to drive discrete (on/off) loads — for example, solenoids, valves, relays, alarms, or contactors.
The prefix “8C‑” denotes it belongs to Series 8 and is likely a coated / protected version (resistant to humidity, corrosion, dust) to suit harsher industrial environments. The suffix “TDOBA1” suggests it is part of the TDO (digital output) family (with variant “A1” design) under the Series 8 ecosystem.
In the control rack, it interfaces with the backplane and connects to the I/O termination (IOTA) or junction modules, which in turn wire out to field devices. It supports channel-level diagnostics, selectable output modes, and “safe state” behavior under fault conditions.
Because it is part of a modular system, you combine it with complementary modules (analog input, digital input, analog output, I/O termination) to build a full control loop or discrete control station.
| Field | Description |
|---|---|
| Brand | Honeywell |
| Series / Platform | Series 8 (S8) / I/O ecosystem for DCS / Experion / similar control systems |
| Module Type | Digital Output (DO) I/O module |
| Role / Function | Drives discrete loads; responds to logic commands by switching outputs |
| Coating / Protection | Coated version (for environmental protection) |
| Naming Logic | “8C‑TDOBA1” = Series 8 + Coated + TDO (digital output) + variant A1 |
This module is part of the same family as 8C‑TDO modules (TDOA, TODB, etc.) and is intended for use in industrial automation, process controls, and discrete actuation systems within environments requiring reliability and diagnostics.
Below is a parameter table for 8C‑TDOBA1. Because detailed datasheet information is scarce, some values are inferred or based on close relatives; these should be verified with manufacturer documentation before final use.
| Parameter | Specification / Typical Value | Notes / Assumptions |
|---|---|---|
| Model | 8C‑TDOBA1 | |
| Module Type | Digital Output (DO) I/O module | |
| Number of Output Channels | 32 channels | |
| Output Mode / Types | Source (positive switching) | |
| Rated Output Voltage | 24 V DC | |
| Max Load Voltage | ~30 V DC | |
| Module Current (Idle) | ~105 mA (module internal draw) | |
| Max Load Current per Channel | ~100 mA | |
| Max Total Module Load Current | ~3.2 A (if all 32 channels active) | |
| Turn‑On / Turn‑Off Time | ≤ 10 ms (typical) | |
| Fail State (Safe State) Options | HOLD LAST / SHED TO SAFE (user configurable per channel) | |
| Power Supply Options | Internal system 24 V or external 24 V field supply (for isolation) | |
| Isolation (System ↔ Field) | ~1000 VAC RMS or equivalent (when external field power used) | |
| Short Circuit / Overload Protection | Yes (per channel or group) | |
| Diagnostics & Alarms | Channel-level fault detection (short, open, diagnostics) | |
| Operating Temperature | 0 °C to +60 °C (typical) | |
| Storage Temperature | −40 °C to +85 °C | |
| Dimensions | Approx. 221 mm × 121 mm × 63 mm (22.1 cm × 12.1 cm × 6.3 cm) | |
| Weight | ~0.35 kg | |
| Coating / Environmental Protection | Coated version, designed to resist moisture, dust, corrosion | |
| Mounting / Interface | Plug into I/O rack / backplane; mates with I/O termination assembly |
Caveats:
Some modules in the same family (e.g. 8C‑TDODA1, 8C‑TDODB1) have similar dimensions (22.1 × 12.1 × 6.3 cm) and similar weight (~0.35 kg).
The operating temperature range is often quoted for DO modules in Series 8 as 0 to 60 °C.
The coating enhances tolerance to harsher ambient conditions (humidity, dust, chemical vapors).
The fail state and diagnostics features are common in this class of modules.
The 8C‑TDOBA1 module is suited to many industrial and automation scenarios where discrete control is needed:
In process control plants (chemical, petrochemical, pharmaceutical) to drive valves, actuators, alarms.
In safety / shutdown systems (ESD, interlocks) where outputs must transition to safe states upon faults.
In manufacturing automation to control relays, motors, solenoids.
In power & utility installations to manage discrete auxiliaries, switching devices.
In water & wastewater treatment for pump/valve control.
In oil & gas / pipeline systems for local actuation and discrete controls.
In distributed control / DCS systems combined with analog I/O modules to build full control stations.
In environments requiring diagnostics, protection, and long-term reliability under harsh conditions.
Because the module supports per-channel diagnostics, short-circuit protection, and safe-state behavior, it is especially useful where fault tolerance and predictable failure behavior are critical.
Here are the main strengths and selling points of 8C‑TDOBA1 compared with simpler or legacy DO modules:
High Channel Density — 32 outputs in a single module saves rack space.
Configurable Fail State — Channels can be set to hold last value or move to safe value upon fault, improving reliability.
Dual Supply / Isolation Option — External power supply option allows galvanic isolation between system and field power.
Diagnostics & Protection — Detects faults, short circuits, open loads, and communicates that to the control system.
Environmental Coating — The coated version resists moisture, dust, chemical vapor corrosion, improving lifetime in harsh sites.
Standardized Dimensions & Integration — Compatible with Series 8 racks, bus architecture, and I/O termination modules.
Fast Switching — Typical on/off times ≤10 ms support moderate-speed discrete control.
Simplifies Wiring & Maintenance — Centralizes discrete output functions, easing field wiring, troubleshooting, and module replacement.
These advantages make it a robust choice in industrial control, especially where environmental conditions are challenging or where downtime is costly.
Below are 5 digital output modules or adjacent DO modules in the same family (Series 8 / co‑located modules) that are either similar or complementary.
| Model | Function / Variant | Key Specs / Features |
|---|---|---|
| 8C‑TDODA1 | Non‑redundant digital output module | 32 channels, same physical layout, switch-mode DO |
| 8C‑TDODB1 | Redundant or variant DO module | 32 channels, supports redundancy or dual path options |
| 8C‑PDODA1 | Coated DO module in P‑bus architecture | 32 channels, coated, part of same DO family |
| 8C‑TDOD51 | Lower channel count DO module | 16 outputs, smaller form factor |
| 8C‑TDOCA1 | Alternate DO variant (coated alternate version) | 32 outputs, alternate switching / isolation arrangement |
These modules may differ in redundancy support, channel count, coating, form factor, or internal isolation. In system design, you might mix them depending on output counts, reliability needs, or space constraints.
Here are 5 well-known Honeywell modules used in the same ecosystem but providing other functionalities (analog, input, controller, etc.):
| Model | Module Type / Role | Key Specs / Notes |
|---|---|---|
| 8C‑TAIDB1 | Analog Input (differential) | 4–20 mA inputs, high accuracy, coating |
| 8C‑TAIXB1 | Analog Input (single‑ended) | Supports alternate analog signal ranges |
| 8C‑PCNT03 | Process / Control CPU | Executes logic, coordinates I/O |
| 8C‑PCNT05 | Higher performance controller | More memory, speed for complex tasks |
| 8U‑TDOBA1 | Uncoated DO module | Similar function but without environmental protection |
Q1: What is the primary purpose of the 8C‑TDOBA1 module?
A1: It provides discrete (on/off) outputs under control from the logic system to drive actuators, relays, valves, etc.
Q2: How many output channels does 8C‑TDOBA1 support?
A2: It supports 32 discrete output channels.
Q3: What is the typical output voltage and current rating per channel?
A3: The output is 24 V DC (typical) with a per-channel load current limit of around 100 mA.
Q4: Does it support safe or fault state behavior?
A4: Yes—each channel can be configured to hold its last state or be forced to a safe state (e.g. off) when a fault occurs.
Q5: Can it isolate field and system power?
A5: Yes. If an external 24 V field supply is used, the module can provide galvanic isolation between system and field sides.
Q6: What is its typical turn-on / turn-off time?
A6: The switching (on/off) response is up to 10 ms in the worst case.
Q7: What environmental conditions can it tolerate?
A7: Operating range: 0 °C to 60 °C; storage: −40 °C to +85 °C. The coated version enhances resistance to moisture, dust, and corrosion.
Q8: How is fault detection handled?
A8: The module supports diagnostics to detect short circuits, open loads, or channel faults and report them to the control system.
Q9: Can the module be replaced during operation (hot-swap)?
A9: Hot-swapping depends on system support. The module is modular, but safe replacement should follow system procedures to avoid signal loss.
Q10: What should I check when selecting this module?
A10: Verify channel count needed, load current per output, environmental conditions, whether coating protection is required, required isolation, and compatibility with the I/O termination modules and backplane.
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