B1 PROFIBUS DP repeater

B1 PROFIBUS DP repeater

The B1 repeater is a compact device for extending and stabilizing a PROFIBUS DP network. It separates the network into two galvanically isolated segments and regenerates the communication signal (amplifies and cleans it). With the repeater, additional PROFIBUS stations can be connected to the network (we recommend only 5 to 10 stations per segment – see text below) and the cable length can be extended (length depends on the transmission speed). Installation is quick, with no addressing required and no changes needed to the configuration of the PROFIBUS Master station.

Key Features

• Galvanic isolation between segments
• Amplification and regeneration of the communication signal
• Built-in switchable bus termination
• Redundant power supply with LED indication and automatic switchover
• Diagnostics via DB9 port (ProfiTrace) and status LEDs
• Transparent for all PROFIBUS DP protocols, also suitable for PROFIsafe and MPI
• Automatic speed detection from 9.6 kbps to 12 Mbps
• Unlimited cascading of segments
• Installation without the need for addressing

Why choose the B1 PROFIBUS DP repeater?

• Enables network expansion when the segment has reached the limit of 31 stations
• Extends cable length when the maximum segment length is exceeded
• Simplifies troubleshooting and maintenance by dividing the network into smaller, isolated segments
• Reliably protects against short-circuit transfer to the other segment
• Ensures stable and robust communication in the PROFIBUS DP network through signal regeneration, smoothing, and digital error filtering
• Redundant power supply minimizes the risk of failure
• Provides fast PROFIBUS diagnostics and reduces downtime
• Easy installation without PLC configuration changes or device addressing

The repeater also serves as a measurement point

On the front of the repeater, there is a CANON DB9 connector that allows a programmer to connect a computer and program the PROFIBUS Master station. In addition, this port functions as a measurement point for connecting the ProfiTrace 2 tester.

When the tester is connected via the front connector, it is directly linked to the second (lower) segment, while remaining galvanically isolated from the first (upper) segment. If the ProfiTrace 2 tester shows low voltage on stations or a damaged signal in the oscilloscope, the issue lies with the stations connected to the second (lower) segment – please take note.

Description of the B1 PROFIBUS Repeater.

Perfect galvanic isolation of both segments

The advanced electronics of the B1 repeater allow unlimited cascading of repeaters in series (unlike competing repeaters), so the usual maximum of 9 repeaters in a cascade does not apply.

The B1 repeater provides 100% short-circuit protection. This means that if the A/B lines in segment 1 are shorted together, the short does not pass through to segment 2. This behavior is naturally expected from a repeater, but unfortunately, it is not the case for many other repeaters on the market.

Additionally, network data is continuously monitored for transients, which the B1 repeater digitally smooths. Our customers report that they prefer the B1 PROFIBUS repeater (or ProfiHub multirepeaters) specifically for the superior galvanic isolation between segments, which helps minimize PROFIBUS network downtime.

Demonstration of signal quality at PROFIBUS stations in a small network. Above is the network without the connected repeater, below is the network after connecting the B1 repeater.

Basic wiring diagram of PROFIBUS repeater B1. The repeater terminates the first PROFIBUS segment 1 and creates a new PROFIBUS segment 2. The PRFIBUS network is strengthened, more stable and more robust.

Preferably less PROFIBUS stations in the segment

Based on our experience, we recommend that customers do not have up to 31 PROFIBUS stations per segment, because 31 stations means 31 potential causes of problems that can cause signal reflections in the PROFIBUS cable. This reflection increases with the length of the segment and eventually becomes so large that it usually shuts down the farthest station. We therefore recommend our customers to deploy a maximum of 5-10 PROFIBUS stations in one segment, then connect a B1 repeater and another segment with 10 stations, etc. This will significantly reduce the time to find the error in case of problems with the PROFIBUS network, because the cause and effect can usually be found in only one segment.

How many repeaters to install?

A new segment is created with each newly installed PROFIBUS repeater. If you have a larger PROFIBUS network and e.g. 3 repeaters installed in it, then you have a total of 4 galvanically separated segments in the network. This is correct from the point of view of signal strength, but it often happens that the PROFIBUS network is actually not clear, you do not know which stations are in which segment, and in the case of measurements it is more difficult to map exactly in which segment you are measuring and which stations are part of it. The worst situation occurs during an outage, because then this opacity is compounded by the pressure to ramp up production, and it's trouble.

We recommend that our customers install a maximum of 2-3 classic PROFIBUS B1 repeaters in one network so that they always have a clear overview of what is connected where. 

Comparison of the dimensions of the B1 repeaters in a star. This wiring is not recommended and it is better to choose multi-repeater ProfiHub B2 or B5.

 If you need to install multiple PROFIBUS repeaters, consider deploying a ProfiHub multirepeater instead. The ProfiHub is the ideal tool for connecting a PROFIBUS network into a star because you take up less space on the DIN rail, you have an extra connection point for each channel and it is a more cost-effective solution.

Compared to what, you ask? In our measurements, we often find multiple classical PROFIBUS repeaters connected to each other, i.e. the upper part is interconnected and the individual galvanically separated PROFIBUS branches from the lower segments go out to the technology. In this way, it is possible to make a star connection, but it is an unfortunate solution in all respects. 

Example of the wiring of the PROFIBUS repeater B1, where the upper segment 1 is through and only the lower segment 2 is galvanically isolated.

Wiring example of the PROFIBUS repeater B1, where the upper segment 1 is through and the lower segment 2 is also through. The entire segment 1 is galvanically separated from segment 2.