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Reliable optical data transmission in PROFIBUS networks

The Anybus ComBricks Fibre Optic Ring module for single-mode technology (ComBricks FO Ring SM) ensures reliable optical data transmission in PROFIBUS networks. This multifunctional module is specifically designed to create optical redundant ring topologies with single-mode fibre optics. It allows long cable distances of up to 30 km and galvanic isolation between devices and segments. The ComBricks FO Ring SM module is especially suitable for applications in heavy EMC environments such as water treatment, mines and tanks.

The ComBricks FO Ring SM module contains diagnostic LEDs which indicates the detection of a low level on the optics. Just like any other communication module, the channels are connected directly to the ProfiTrace OE core in the Head Station. An advanced email functionality will alert you when faults like low-level or broken ring arise. Because busmonitor data is directly available in the web server, it allows technicians to optimally maintain a PROFIBUS installation.

ComBricks FO Ring SM can be placed side by side with repeater modules allowing spur line diagnostics. It can also easily be used as a fully dedicated fibre optic module mixed with copper segments. The advanced 12 Mbps core of the fibre optic module can be cascaded unlimited with other fibre modules. 

Product Information

Distinctive features

• Suitable for up to 30 km of single-mode cable
• Long cable distances
• Galvanic isolation between devices and segments
• Suitable for point-to-point, star, bus, & ring topologies
• EKS, Compatible with our ProfiHub F.optic modules

Figure 1 – Ring structure with single-mode fibre optics


Figure 2 – Point-to-point in a hub topology with single-mode fibre optics


L x W x H: 

146 x 25 x 101 mm (including backplane)

Weight: 121 g (excluding plug-able fibre optic connector and packing material)
Mounting DIN-rail type 35mm × 7,5mm (EN 50022, BS 5584, DIN 46277-3)

Ambient conditions

Operating temperature range

0° to +60° Celsius (for mounting position see manual)

32° to +140° Fahrenheit

Isolation class

IP 20 (IEC/EN 60529, DIN 40050)


PROFIBUS networks

4 (set by dipswitches or web server)


Max. 10 (positioned in the first 10 slots)

Power supply 

Provided through the backplane

Typical backplane current at 5.75 VDC

400 mA (at 5.72 VDC)

Max. backplane current at 5.75 VDC

600 mA (at 5.72 VDC) At this current consumption the module is switched OFF from the backplane. Occurs when the module is faulty, e.g. internal short circuit.

Compatible backplane units

101-200011, 101-200022, 101-200023, 101-200024,


Head Station firmware 1.288 and higher

Protocol specifications

Supported Protocols

DP-V0, DP- V1, DP-V2, FDL, MPI, FMS, PROFIsafe, PROFIdrive and any other FDL-based protocol


No bus address required

Transmission speed

9.6 kbps … 12 Mbps (including 45.45 kbps)

Transmission speed detection time Auto detect (< 10 s detection and 50 s baudrate switchover time)

The total delay ring structure

TSLOT  ≥  MaxTSDR + ((FOlength

FOlength          =    Total length of fibre optic cable in the ring in km

FOdelay           =    Delay of fibre optic cable per km in bit times (see table)

NFO-modules  =    Number of fibre optic modules in the ring

Ndelay             =    Delay of one fibre optic module (see table)

The delay time is multiplied by 2 for a request and response message.

Baudrate MaxTSDR
12 Mbps 800 60 47
6 Mbps 450 30 25
3 Mbps 250 15 14.5
1.5 Mbps 150 7.5 9
500 kbps 100 2.5 5
187.5 kbps 60 0.94 4.5
93.75 kbps 60 0.47 4.5
45.45 kbps 400 0.23 4.5
19.2 kbps 60 0.1 4
9.6 kbps 60 0.05 4


FOdelay = (FOcable_length  / FOcable latency ) / Bittime 

example FOdelay, 1km, 1.5Mbps:

(1000 m / 200 µsec/m) / 0.666 µsec = 7.5 Tbit/km

Example 1:  1.5 Mbps, 5 km FO cable (total ring length), 6 FO ring modules

TSLOT  ≥  MaxTSDR + ((FOlength x FOdelay) + (NFO-modules x Ndelay)) x 2

TSLOT  ≥ 150 + ((5 x 7.5) + (6 x 9)) x 2 ≥ 333 bit times

Example 2:  6 Mbps, 25 km FO cable (total ring length), 10 FO ring modules

TSLOT  ≥  MaxTSDR + ((FOlength x FOdelay) + (NFO-modules x Ndelay)) x 2

TSLOT  ≥ 450 + ((25 x 30) + (10 x 25)) x 2 ≥ 2450 bit times 

Jitter per message frame

0.0625 Tbit at 9.6 Kbps – 3 Mbps

0.125 Tbit at 6 Mbps

0.25 Tbit at 12 Mbps

Deviation 2 Tbit times for received messages is allowed and is corrected to nominal speed when transmitted (over the complete message)

Fibre optic specifications

Fiber Optic wavelength

Single mode 1310 nm

Cable type

Fibre 9 / 125 µm (OS1 and OS2 compatible)

Cable length

Max. 30 km (baudrate independent)

Optical budget


Optical Loss

0,4dB per km


4 x ST/BFOC (2 channels)


Ring, point-to-point (direct, hub, split, star)

Cascading depth

No limit, only the bus parameter limitation of the master



  OFF Blinking ON
RDY The module has NOT been powered/initialised yet. Head Station is initialising or updating the module. The module has been initialised and is operational
RX1 / RX2 NO signal or NO valid telegrams detected on this channel, or the channel is off. 1 or more devices are communicating on this channel. A fibre optic cable is connected and the link is established correctly
LV1 / LV2 The signal quality is good, or the channel is off.  Not possible Low signal, received messages can still be decoded
ER1 / ER2 No errors or the channel is off. Not possible No baud rate detected or no connection/signal

Standard and approvals


EMC Directive 2014/30/EU, class B Digital Device

RoHS Directive 2011/65/EU


47 CFR 15, Unintentional Radiator, class B Digital Device.


Report reference: E468970

Standards for safety: UL 508 – Industrial Control Equipment CSA C22.2 No. 142-M1987 – Industrial Control Equipment

Complies with 21 CFR 1040.10 and 1040.11, Class 1 (I) except for deviations pursuant to Laser Notice No. 50, dated June 24, 2007


Head Station firmware

1.288 and higher

Order Codes   101-201531
Included Components Anybus ComBricks, backplane socket
Warranty  1 year

Book your product

We are fully committed to providing our customers with the very best products and customer service. We believe in going the extra mile to ensure that each customer is satisfied with our products and solutions. We have the experience and the reputation in the field to deliver the products customers need to expedite their projects and assure quality every step of the way.

Our expertise lies in establishing, maintaining, and leveraging plant data for business benefit. Through our innovative solutions, we work alongside you to streamline processes, enhance efficiency, and reduce costly downtime.


Main: +27 (11) 548 9960
Sales: +27 (11) 548 9970