Redundant modem with single I/O
Keeps two TB840/TB840A modem positions while serving a non-redundant I/O arrangement.
ABB TU841 Redundant Optical ModuleBus Modem MTU for Single I/O
ABB TU841 redundant optical module
ABB PLC Bus Modem MTU
Single I/O optical module
Brand Name:
ABB
Model Number:
TU841
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Product Details
ABB Article Number:
3BSE020848R1
Highlight:
ABB TU841 redundant optical module
,ABB PLC Bus Modem MTU
,Single I/O optical module
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Product Description
ABB · TU841
ABB TU841 Redundant Optical ModuleBus Modem MTU for Single I/O
ABB TU841 passive MTU for redundant TB840/TB840A Optical ModuleBus modem configuration with one electrical ModuleBus, non-redundant I/O and 24 V DC input.
TypeRedundant modem termination unit
SystemABB S800 I/O / Optical ModuleBus
FocusRedundant modem, single I/O
BrandABB
TU841 availability, lead time and order review
Send RFQProduct Introduction
TU841 is the passive S800 I/O termination unit for two TB840/TB840A Optical ModuleBus modems when the modem function is redundant but the connected I/O is non-redundant.
Engineering note: TU841 and TU840 do not describe the same I/O redundancy. TU841 uses a single electrical ModuleBus for non-redundant I/O.
Technical Specifications
Select a category to view its specifications. All categories are closed by default.
Identification & configurationView 6 specificationsHide specifications⌄
| ABB article number | 3BSE020848R1 |
|---|---|
| Product type | Passive Module Termination Unit |
| Modem positions | Two TB840/TB840A |
| Electrical ModuleBus | One |
| I/O arrangement | Single / non-redundant I/O |
| Cluster address | Rotary switch, 1 to 7 |
Redundancy & powerView 5 specificationsHide specifications⌄
| Module redundancy | Yes |
|---|---|
| Cable redundancy | No |
| Power arrangement | Single power |
| Power input | 24 V DC (19.2–30 V DC) |
| Hot swap | No |
Terminals, insulation & sizeView 7 specificationsHide specifications⌄
| Acceptable wire size | Solid/stranded 0.2–2.5 mm², 24–12 AWG |
|---|---|
| Recommended terminal torque | 0.5 Nm |
| Dielectric test voltage | 500 V AC |
| Rated insulation voltage | 50 V |
| Dimensions | 124 × 186.5 × 47 mm |
| Weight | 450 g |
| Protection rating | IP20 |
Compatibility & Replacement
Confirmed modem fit. ABB specifies TU841 for redundant configuration of TB840/TB840A Optical ModuleBus modems.
Confirmed I/O scope. The TU841 configuration is for non-redundant I/O on one electrical ModuleBus. Do not substitute redundancy assumptions from TU840.
Applications & Fault Scenarios
Legacy cluster maintenance
Supports restoration of an existing Optical ModuleBus cluster whose design separates modem redundancy from I/O redundancy.
Modem switchover alarm
Check both modem positions, the single electrical ModuleBus and the documented cluster address.
I/O outage despite second modem
A second modem does not make the I/O redundant; diagnose the single I/O and ModuleBus path directly.
Wrong base selected during repair
Compare TU841 versus TU840 function before installation; the I/O redundancy arrangement is different.
Independent spare-parts support
Amikon can review the exact part number, installed system, quantity, destination and required date before quotation.
Pre-outage checkpoints
- Confirm the design calls for single, non-redundant I/O.
- Record the cluster address from 1 to 7.
- Identify the single electrical ModuleBus connection.
- Verify both TB840/TB840A modem positions after work.
Amikon Supply & Service
Independent multi-brand support for maintenance, outage and legacy-system requirements.
Order reviewPart number, quantity, destination, required date and system model checked.
Inspection & testingLabel, condition and serial checks; testing when agreed.
Packing & dispatchProtective export packing and delivery coordination.
DOA, returns, warranty & supportAfter-sales review under the quoted return and warranty terms.
Request for Quotation
- Part Number
- Quantity
- Destination
- Required Date
- Machine / System Model
Direct RFQ contactMiya ZhengIndustrial automation spare-parts support
Emailsales@amikon.cn
WhatsApp+86 180 2077 6792
Websitedcscontroller.com
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These models are listed only as independent sourcing references. They are not substitutes for TU841. Compatibility, configuration and stock must be confirmed separately for each item.
TU841 FAQ
How should a buyer distinguish ABB TU841 from similar redundant MTUs?
Match the complete TU841 model and ABB article identification and verify the connected I/O arrangement. Visual similarity is not sufficient for purchasing.
What should an ABB TU841 buyer confirm about the installed redundancy arrangement?
State how the existing MTU is used in the S800 I/O station and provide the connected module, cabinet position and label photos so the requirement can be checked against ABB documentation.
Can current stock, condition and lead time for ABB TU841 be confirmed from this page?
No. Stock, condition, inspection scope and lead time change by offer and must be confirmed in the live quotation for ABB TU841.
What pre-shipment evidence can I request for ABB TU841?
Request clear label, condition and serial-number photos plus the agreed inspection or testing record for ABB TU841 before dispatch.
How should I submit an urgent shutdown requirement for ABB TU841?
Send the exact part number, quantity, destination, required date, machine or system model and failure context. Priority routing starts after the ABB TU841 identity is confirmed.
What DOA, return and warranty terms apply to ABB TU841?
They are defined in the quotation. If ABB TU841 arrives DOA or does not match the purchase order, report the serial number, label, packaging and fault evidence promptly for after-sales review.
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