S800L
Compact I/O
AI801, AO801, DI801–DI803 and DO801–DO802. Space-saving and suited to basic PLC applications; S800L does not use standard S800 MTUs.
Practical selection guide · 2026 edition
ABB S800 I/O:choose the rightmodule the firsttime.
A field-ready reference for AI, AO, DI, DO and DP modules—complete with real specifications, communication topology, troubleshooting patterns and a purchasing checklist.
AI / AODI / DOPulse & frequencyHART · Redundancy · IS
● SYSTEM ONLINES800 / 800xA
AI845 · 8 ch · HART · S/R
DI840 · 16 ch · 24 V · S/R
DP840 · 8 ch · 0.5–20 kHz
READY FOR SELECTION_
40+module types
HARTpass-through capable
Complete technical guide
Find the right S800 I/O answer faster
This guide is organized around the questions engineers and buyers ask most: which module fits the signal, how the station communicates, what fails in the field and what must be confirmed before purchase.
Model list
AI · AO · DI · DO · DP
Architecture
FCI · ModuleBus · MTU
Troubleshooting
Diagnostics and replacement
Buying checklist
Compatibility and quotation
Search intent map
What is ABB S800 I/O used for?
S800 I/O is a distributed process I/O platform for connecting field instruments and actuators to AC 800M, System 800xA and compatible controllers. The system is commonly evaluated for signal density, HART, redundancy, SOE, hazardous areas and maintenance continuity.
AI
Transmitters, RTD and thermocouples
AO
Valves, actuators and control loops
DI / DO
Status, alarms, solenoids and relays
DP
Pulse, speed, frequency and NAMUR
01 / Core selection
Common models at a glance
Use signal type, channel count, isolation, diagnostics and redundancy—not the model number alone—to make the selection.
| Model | Channels | Actual signal / rating | Best fit |
|---|---|---|---|
| AI810 | 8 | 0/4–20 mA, 0–10 V, 12-bit, single-ended | Standard transmitters |
| AI815 | 8 | 0/4–20 mA, HART, 12-bit, limited transmitter supply | Smart transmitters |
| AI830A | 8 | Pt100, Ni100/120, Cu10, resistance; 3-wire | RTD temperature |
| AI845 | 8 | 0/4–20 mA, HART, single or redundant, diagnostics | Critical smart loops |
| AO810V2 | 8 | 0/4–20 mA, 14-bit, max. load 850 Ω | Standard analog output |
| AO820 | 4 | ±20 mA / ±10 V, isolated channels, 12-bit + sign | Isolated current or voltage |
| DI810 | 16 | 24 V DC, two groups of 8, current sink | Standard digital input |
| DI840 | 16 | 24 V DC, single or redundant, diagnostics | Redundant DI architecture |
| DO810 | 16 | 24 V DC transistor, sourcing, 0.5 A/ch | Solenoids and status outputs |
| DO820 | 8 | Relay, 5–250 V AC/DC, up to 3 A | AC or relay loads |
| DP820 | 2 | 0.25 Hz–1.5 MHz, 5/12 V DC | High-speed pulse counting |
| DP840 | 8 | 0.5–20 kHz, 12/24 V DC or NAMUR | Frequency and NAMUR inputs |
Model families
Beyond the standard modules
The complete family includes compact S800L modules, high-integrity modules and intrinsically safe modules. These are not drop-in substitutions for standard I/O without checking the controller, MTU and safety design.
High integrity
SIL3 architecture
AI880A, DI880 and DO880 are used only within an approved high-integrity architecture with the required controller and safety configuration.
Intrinsic safety
Hazardous-area signals
AI890, AI893, AI895, AO890, AO895, DI890 and DO890 provide IS interfaces for approved field circuits and installation conditions.
MTU and interface matching
A module is only one part of the order
The most common procurement mistake is quoting the I/O module without confirming the termination unit and communication interface.
| System part | Examples | What it does | What to verify |
|---|---|---|---|
| FCI | CI801, CI840A, CI845 | Connects the controller or network to the S800 station | Protocol, redundancy, firmware and controller support |
| MTU | TU810, TU830, TU842, TU846, TU847, TU890 | Provides terminals, mechanical keying and ModuleBus connection | Signal voltage, orientation, redundancy and IS/non-IS type |
| ModuleBus | TB807, TB840, optical extensions | Connects the FCI and I/O clusters | Cluster distance, optical expansion and termination |
| Power | 24 V supply, redundant supply, voter | Powers the I/O station and supports availability | Load, redundancy and cabinet power budget |
02 / Selection logic
Which module should you choose?
Analog input
AI810 vs AI815 vs AI845
Choose AI810 for standard signals. Move to AI815 for HART. Choose AI845 when HART, redundancy and onboard diagnostics are all required.
Digital input
DI810 vs DI814
Both are 24 V families, but their current direction differs. Confirm whether the field device requires a sinking or sourcing input before ordering.
Output
DO810 vs DO820
DO810 is a 24 V transistor output. DO820 is a relay output for wider AC/DC voltage ranges and larger switching loads.
03 / Communication topology
Typical S800 I/O architecture
The module communicates through the fieldbus communication interface; field wiring lands on the matching MTU.
PROFIBUS / REDUNDANT MODULEBUS EXAMPLE
AC 800MPM8xx / CI854A
→CI801 / CI840APROFIBUS DP-V1
→ModuleBusTB807 / TB840
→S800 modulesAI · AO · DI · DO · DP
→MTU + field devicesTU810 · TU830 · TU842
For Ethernet-based architectures, CI845 connects S800 I/O through an Ethernet FCI. Actual terminal wiring must follow the module-specific ABB manual and selected MTU.
04 / Maintenance
Common faults in the field
No signal
AI reads zero or overrange
Check loop power, polarity, current/voltage mode, transmitter supply, shield termination and the configured channel type.
Communication
ModuleBus or fieldbus loss
Check 24 V supply, PROFIBUS termination, node configuration, ModuleBus termination, cable condition and firmware compatibility.
Output trip
DO does not energize the load
Confirm sourcing or sinking logic, load current, external supply, inductive suppression and whether the relay contact is NO or NC.
Field maintenance pattern
A practical replacement workflow is: identify the failed module in 800xA, verify the exact article number and MTU, replace according to the ABB procedure, check LEDs, perform a calibrated loop test, then verify the value in the controller and HMI. Never substitute a module based only on channel count.
05 / Before you buy
Purchasing checklist
Send these details to reduce quotation delays and avoid an incompatible replacement.
Confirm the technical fit
- Exact model and complete ABB article number
- Quantity and new / refurbished requirement
- Controller and 800xA system version
- CI801, CI840A or CI845 interface
- MTU model and terminal arrangement
- Signal type, voltage, current and channel count
- HART, SOE, redundancy, SIL or intrinsic safety
Ask the supplier to confirm
- Hardware revision and firmware compatibility
- Original, refurbished or repaired status
- Test report and warranty period
- Online replacement support
- Certificates for hazardous or marine applications
- Stock status and delivery date
- Export packing and destination requirements
Need a compatibility check?
Send the model. We’ll help verify the fit.
Share the module number, MTU, controller and quantity. We can help with selection, replacement and quotation.
FAQ
ABB S800 I/O questions engineers ask
▾ What is the difference between S800 and S800L?
S800 is the broader process I/O platform with advanced diagnostics, HART, redundancy and time-stamped events. S800L is the more compact, basic-function I/O option and uses an integrated terminal arrangement rather than standard S800 MTUs.
▾ Can an AI810 be replaced by an AI815?
Not automatically. AI815 adds HART and has different signal and transmitter-power characteristics. Verify the controller configuration, HART requirement, MTU and field wiring before substitution.
▾ What is required for redundant S800 I/O?
Depending on the architecture, redundancy may require redundant fieldbus, CI840A interfaces, appropriate MTUs, ModuleBus wiring and redundant I/O modules such as AI845 or DI840.
▾ Can S800 I/O be used in a hazardous area?
Use only the appropriate intrinsically safe modules, MTUs and approved installation design. Standard S800 modules should not be treated as intrinsically safe modules.
Long-tail search topics
Related ABB S800 I/O searches
ABB AI810 datasheetABB DI810 replacementABB DO810 24 V outputABB S800 HART moduleCI840A redundancyS800 MTU selectionS800 I/O troubleshootingS800L vs S800S800 SIL3 I/OS800 intrinsic safety