The 3BSE091723R1 ABB RLM02 is a PROFIBUS Redundancy Link Module designed for PROFIBUS DP/FMS line redundancy. It converts a single non-redundant PROFIBUS line into two redundant RS485 lines, or combines two redundant lines into one non-redundant PROFIBUS line.
RLM02 is intended for industrial automation networks where communication availability is important. It can be installed directly after a PROFIBUS master, before a bus segment containing multiple slaves, or in front of an individual field device. The module monitors the three PROFIBUS lines and automatically selects the available communication path.
Product Identification
| Item | Details |
|---|---|
| Brand | ABB |
| Product ID | 3BSE091723R1 |
| Type Designation | RLM02 |
| Product Name | PROFIBUS Redundancy Link Module |
| Network | PROFIBUS DP/FMS |
| Main Function | PROFIBUS line redundancy |
| Interfaces | 3 PROFIBUS ports |
| Interface Type | RS485 |
| Transmission Rate | 9.6 kbit/s to 12 Mbit/s |
| Mounting | DIN mounting rail |
| Power Supply | 24 V DC |
| Power Supply Range | +20 to +33 V DC |
| Typical Current | 120 mA at 24 V DC |
| Redundant Power Supply | Supported |
| Line Monitoring | Supported |
| Repeater Function | Supported |
ABB's official RLM02 documentation identifies 3BSE091723R1 as the article number and specifies the module for PROFIBUS DP/FMS line redundancy.
What the RLM02 Does
The main purpose of the RLM02 is to add line redundancy to a PROFIBUS network.
In a conventional non-redundant network, a single PROFIBUS line connects the master and field devices. A failure in that communication path can interrupt communication with downstream devices.
RLM02 provides an A/B redundant line arrangement. Data received through the available redundant path is forwarded to the non-redundant PROFIBUS connection. In the opposite direction, a single PROFIBUS line can be split into two redundant RS485 lines.
The module therefore serves as a dedicated network component rather than as a conventional PROFIBUS slave.
Three PROFIBUS Interfaces
RLM02 has three PROFIBUS ports:
- A - redundant PROFIBUS line A
- B - redundant PROFIBUS line B
- M - non-redundant PROFIBUS line
ABB describes the three interfaces as part of the module's line-redundancy function. The RLM02 monitors all three lines for activity and error conditions and controls the forwarding of valid PROFIBUS telegrams between the redundant and non-redundant sides.
This three-port arrangement is one of the most useful identification characteristics when matching an RLM02 replacement.
PROFIBUS Communication
The RLM02 supports PROFIBUS DP/FMS and transmission rates from 9.6 kbit/s to 12 Mbit/s. It is transparent to PROFIBUS configuration and does not require its own slave address.
The module can serve up to 31 PROFIBUS stations on each RLM02 PROFIBUS interface. ABB also notes that repeaters and media converters can be used when additional network length or station capacity is required.
This makes RLM02 particularly relevant to PROFIBUS networks where maintaining communication through a single cable or segment failure is more important than simply adding another fieldbus interface.
Automatic Line Selection
RLM02 performs automatic selection between the two redundant communication paths.
When valid data arrives through line A or line B, the module forwards the appropriate telegram to the non-redundant M connection. If a fault is detected on one redundant line, the control logic switches to the other available path.
The module also monitors communication activity and error status on the three connected lines. Fault conditions are indicated locally through the front-panel status LEDs and can additionally be made available through the module's signaling contact.
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Repeater Function
RLM02 is not only a redundancy device. ABB also specifies repeater functionality.
The module regenerates the signal form and amplitude of incoming PROFIBUS data, helping maintain the quality of the RS485 communication signal within the supported network architecture.
This is particularly useful when RLM02 is installed as part of a larger PROFIBUS infrastructure rather than simply between one master and one field device.
Power Supply
The RLM02 supports a redundant 24 V DC power supply.
ABB specifies a supply range of +20 to +33 V DC, with a typical current consumption of 120 mA at 24 V DC. The module monitors the availability of the connected supply voltages and reports power-supply faults.
For installations requiring additional availability, both supply inputs can be used. ABB documentation also describes the arrangement required when only a single power supply is connected.
Installation and Status Monitoring
The RLM02 is designed for straightforward installation on a DIN mounting rail. ABB lists status and error indication as part of the module's standard features.
The front-panel indicators provide local information about communication activity, errors and power status. A potential-free signaling contact is also available for diagnostic purposes.
This makes the module practical for maintenance of installed PROFIBUS networks because communication faults can be identified at the network component without relying solely on the higher-level control system.
Where RLM02 Can Be Installed
ABB identifies several suitable positions for the RLM02 within a PROFIBUS network.
It can be installed:
- Directly after a PROFIBUS master
- Before a PROFIBUS segment containing several slaves
- Before an individual PROFIBUS slave
- Between a non-redundant PROFIBUS line and a redundant A/B network
Field devices equipped with redundant couplers can connect directly to a PROFIBUS network made redundant by RLM02. Devices with only one PROFIBUS interface can be assigned to either the A or B line.
ABB System Compatibility
RLM02 appears in ABB documentation for several automation environments and is listed within ABB's PROFIBUS network component portfolio.
ABB's System 800xA catalog identifies 3BSE091723R1 as the RLM02 PROFIBUS Redundancy Link Module. ABB's Freelance documentation also lists RLM02 as a PROFIBUS network component for converting non-redundant PROFIBUS DP lines into redundant lines and vice versa.
This makes the product relevant to maintenance and replacement work involving ABB System 800xA, Freelance and PROFIBUS-based control installations.
Technical Data
| Parameter | ABB RLM02 Data |
|---|---|
| Article Number | 3BSE091723R1 |
| Type | RLM02 |
| Communication | PROFIBUS DP/FMS |
| Number of PROFIBUS Ports | 3 |
| Interface | RS485 |
| Transmission Rate | 9.6 kbit/s–12 Mbit/s |
| Maximum Stations per Interface | 31 |
| Power Supply | 24 V DC |
| Supply Range | +20 to +33 V DC |
| Typical Current | 120 mA at 24 V DC |
| Redundant Power Supply | Yes |
| Automatic Line Selection | Yes |
| Communication Monitoring | Yes |
| Repeater Function | Yes |
| Status/Error Indication | LED |
| Alarm Contact | Potential-free |
| Mounting | DIN rail |
The table above is based primarily on ABB's official RLM02 product information and data sheet.
RLM02 and PROFIBUS Redundancy
The important distinction when identifying this product is that RLM02 is not simply a PROFIBUS connector, repeater or standard communication interface.
Its primary function is line redundancy.
The basic arrangement can be understood as:
Non-redundant PROFIBUS → RLM02 → Redundant PROFIBUS A/B
or, in the opposite direction:
Redundant PROFIBUS A/B → RLM02 → Non-redundant PROFIBUS
This architecture allows field devices with a single PROFIBUS interface to participate in a redundant PROFIBUS network.
Related ABB PROFIBUS Components
Several ABB products can appear alongside RLM02 in PROFIBUS procurement searches, but they perform different functions.
| ABB Product | Article Number | Main Function |
|---|---|---|
| RLM02 | 3BSE091723R1 | PROFIBUS line redundancy |
| PCO 011 | 3BDZ000371R1 | PROFIBUS DP connector with switchable bus termination |
| PCO 012 | 3BDZ000372R1 | PROFIBUS DP connector with termination and adapter |
ABB's product catalogs list these products within the PROFIBUS network component and PROFIBUS DP accessory groups.
For your website, RLM02 should remain the main product focus, while PCO 011 and PCO 012 can be useful as related PROFIBUS accessory links if those products are added later.
Replacement Identification Guide
When sourcing an RLM02 replacement, the most important identifiers are:
- ABB Product ID: 3BSE091723R1
- Type Designation: RLM02
- Product Name: PROFIBUS Redundancy Link Module
A replacement request should ideally include the complete ABB article number rather than only "PROFIBUS redundancy module," because other ABB PROFIBUS products perform different functions.
It is also useful to confirm that the installed application requires:
- Three PROFIBUS connections
- A/B line redundancy
- PROFIBUS DP/FMS communication
- 24 V DC power
- DIN-rail mounting
FAQ
What is ABB 3BSE091723R1?
3BSE091723R1 is the ABB article number for the RLM02 PROFIBUS Redundancy Link Module.
What is the function of ABB RLM02?
RLM02 converts a non-redundant PROFIBUS line into two redundant RS485 lines, or combines two redundant lines into one non-redundant PROFIBUS line.
How many PROFIBUS ports does RLM02 have?
RLM02 has three PROFIBUS ports, corresponding to the redundant A/B lines and the non-redundant M line.
What PROFIBUS speeds does RLM02 support?
ABB specifies transmission rates from 9.6 kbit/s to 12 Mbit/s.
Does RLM02 require a PROFIBUS slave address?
No. ABB describes RLM02 as transparent for PROFIBUS configuration, meaning it does not require its own slave address.
Can RLM02 use redundant power supplies?
Yes. RLM02 supports a redundant 24 V DC power supply, and its power-supply monitoring can report supply faults.
Is RLM02 a PROFIBUS repeater?
It includes repeater functionality, but its primary purpose is PROFIBUS line redundancy. It regenerates the received signal while also monitoring the three PROFIBUS lines.
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