ProfiHub B5+R PROFIBUS multi-repeater

What is ProfiHub B5+R

The ProfiHub B5+R is a network hub with which you create a star metallic PROFIBUS DP topology for PROFIBUS DP devices.

The maximum number of newly created PROFIBUS DP segments is +5 and all segments are galvanically isolated from each other. Thanks to the ProfiHub multirepeater, interference or a bad signal in one segment does not reach the next segment and does not affect its signal quality.

Example of a new star topology in a PROFIBUS DP network, which we created using the ProfiHub B5+R

Diagnostics

Thanks to the diagnostic LEDs on each segment, it is possible to detect an error before PROFIBUS stops working. In addition, each segment is equipped with a CANON SUB9 connector, which serves perfectly as a measuring point for connecting a PROFIBUS analyzer, e.g. a ProfiTrace 2 tester.

The ProfiHub B5 has an IP20 protection rating. If you need a higher rating, choose the ProfiHub A5 variant with IP65 protection.

Example of the ProfiHub B5+R multirepeater wiring in a rack. It creates 5 new galvanically separated PB segments (C1-C5 cables) from the main PB signal feed (Main Bus)

Perfect galvanic separation of all PROFIBUS segments

The advanced electronics of the ProfiHub multirepeater allows (unlike competing repeaters) unlimited cascading in succession (so the maximum number of 9 repeaters in a cascade does not apply).

The ProfiHub has 100% short circuit protection, i.e. if you short the A/B wires in segment 1 with respect to each other, this short circuit will not pass to the other segments. This behavior is logically expected from a repeater, but unfortunately does not apply to many other repeaters on the market.

In addition, the data on the network is constantly monitored for the presence of skew, which ProfiHub digitally smoothes out. We know from our customers that they prefer ProfiHub multirepeaters precisely because of the better galvanic separation of all segments, which has minimized outages on PROFIBUS networks. 

Thanks to the 100% galvanic isolation of the PROFIBUS segments, the ProfiHub B5+R does not pass a jammed or damaged signal from one segment to another.

The most cost-effective PROFIBUS splitter

The ProfiHub is the ideal tool for connecting a PROFIBUS network into a star because it takes up less space on the DIN rail, you have an extra connection point for each channel and it is even more cost-effective.

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.

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

Less PROFIBUS stations in more segments is better

In our experience, we recommend that customers do not have up to 31 PROFIBUS stations in a 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 that our customers deploy a maximum of 5-10 PROFIBUS stations per segment. In practice, this means that you bring the signal from the MASTER station to the ProfiHub multirepeater (you can then continue further) and connect a maximum of 5-10 stations to each segment. These can be stations always in one rack, stations in one direction from the rack, all inverters / IO peripherals / HMI panels etc. It doesn't really matter because ProfiHub acts as a hub, so it connects everything to everything. It practically doesn't matter what stations you connect to each channel (segment).

This strategy of dividing the network into smaller segments with fewer stations not only significantly increases the robustness of the PROFIBUS network, but in the event of a problem with the PROFIBUS network, it also reduces the time it takes to find the cause of the error, because the cause and effect can usually be found in just one segment.

By placing PROFIBUS stations in multiple galvanically separated segments, the robustness and resilience of the PROFIBUS network to possible interference and faults in other PROFIBUS segments is increased. An error from one segment will not reach the other segment and we can therefore locate the error more quickly.

Redundancy in the PROFIBUS network

If you need to create a second physical metallic connection between two locations in the PROFIBUS network, e.g. due to frequent cable damage, then you can use the redundancy function. You activate this function by switching the rotary switch to position 2 or 5 and the last channels 4 and 5 start to act as a redundant connection between the two ProfiHub modules. In the event of a failure of one cable, the redundant link automatically starts to function.

 Demonstration of redundancy in a PROFIBUS network via the ProfiHub B5+R. If one PROFIBUS cable is damaged, the other cable immediately acts as a backup.

Main advantages

• You create 5 galvanically separated segments (1× original + 5× new).
• You can connect stations in a star or use a tree topology as well.
• Alarm relay contact will alert you when the secondary power supply fails.
• Installation does not require a change in the PB Master station HW configuration (unless the Diagnostics - DP SLAVE function is activated).
• The CANON measurement port on each segment allows you to connect a PB tester and measure each segment separately, from one location.
• LEDs on each segment clearly indicate the communication status - OK, ERROR, no signal.
• You can create a redundant connection to a second ProfiHub module via channels 4 and 5.
• You can set a fixed specific PB speed (which is an effective protection against unwanted network speed reduction in the PB Master station, ProfiHub will not let any speed other than the set speed to continue).
• The small compact design takes up very little space in the rack (de facto replaces 5 side by side connected classic PB repeaters).
• It is a cost-effective solution - 5 side-by-side classic PB repeaters would cost you more 
  
  
  

Permanent PROFIBUS diagnostics

The diagnostic functions of the PROFIBUS communication can be switched on using the rotary switch. The ProfiHub becomes a DP SLAVE station, the address can be set via the SW configuration of the MASTER station or e.g. using the ProfiTrace 2 tester. The user can set the data he wants to receive from the ProfiHub multirepeater via a GSD file. The cyclic data can contain simple statistics as well as complex structures identifying channel problems.

Example of connecting a ComBrick device in a PROFIBUS network for monitoring the PROFIBUS network and as an additional PROFIBUS MASTER. In the viewer, you can then see the data from the ProfiHub B5+R showing events in the PROFIBUS network.

ProfiHub as permanent diagnostics for PROFIBUS

The ProfiHub B5+R in PROFIBUS diagnostics mode acts as a SLAVE station and provides the MASTER station with information about the network and the connected stations. This can be used to create visualization screens in which you can draw the network topology, live-list of stations, statuses of individual stations, captured outages, communication errors, communication statistics, etc.

Diagram of the diagnostics capabilities of the ProfiHub B2+R. The displayed data can be read into the Combricks device and further evaluated in higher-level e.g. SCADA HMI systems.

ProfiHub provides to PROFIBUS MASTER with the following information:

• PROFIBUS speed
• relay alarm status of the ProfiHub station,
• presence of power supply at terminals 1 and 2,
• the states of the termination resistors of the individual segments,
• presence of PROFIBUS signal on each segment,
• Live list of stations of each segment, i.e. which stations are online connected to each segment,
• total PROFIBUS statistics for the entire ProfiHub and statistics for the individual segments:
  • station losses,
  • SYNC messages,
  • repeat queries - total,
  • query retries - sequences,
  • corrupted messages,
  • internal diagnostics,
  • external diagnostics,
  • diagnostics during data exchange.
    
    

The Combricks web page, where you can see the data about the ProfiHub B5+R device that Combricks reads and displays.