ProfiHub B2+R multi-repeater PROFIBUS

PROFIBUS DP Repeater with 3 Segments

The ProfiHub B2+R is equipped with two galvanically isolated transparent repeaters (offering three segments). Each segment can handle 31 devices and a cable length equal to the main bus. To save costs on plugs and to offer flexibility, the repeater contains screw terminals as well as DB9 connectors. Termination for each segment is on-board and switchable.

If bus redundancy is enabled, two segments will form a redundant pair which is completely compatible with the ABB RLM01. An alarm contact is linked to events based on the status of the power supply and the bus redundancy status.

PROFIBUS multi-repeater ProfiHub B2+R wiring example. It creates 2 new galvanically separated PB segments (2x on the right) from the main PB signal input (left)

Main advantages

• Create 2 new galvanically separated segments (1× original + 2× new).
• You can connect stations in a star or use a tree topology.
• 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 2 and 3.
• You can set a specific PB speed permanently (which is an effective protection against unwanted network speed reduction in the PB Master station, the ProfiHub will not let any speed other than the set speed go on).
• The small compact design takes up very little space in the rack (de facto replaces 2 side-by-side PB repeaters).
  
  

Thanks to the 100% galvanic isolation of the PROFIBUS segments, the ProfiHub B2 does not pass a jammed or damaged signal from one segment to another.

Perfect PROFIBUS galvanic separation of all segments

The advanced electronics of the ProfiHub multirepeater allows (unlike competing repeaters) unlimited cascading in succession (i.e. a maximum 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. 

Wiring diagram of the PROFIBUS multirepeater ProfiHub B2+R.

Prefer less PROFIBUS stations in the segment

In 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 lead to 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 e.g. a maximum of 5-10 PROFIBUS stations in one segment. In practice, this means that you bring the signal from the MASTER station into the ProfiHub multirepeater (you can then continue further) and connect a maximum of 5-10 stations per 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 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, you will also reduce the time to find the cause of the error, as the cause and effect can usually only be found in one segment.

All connected PROFIBUS cables (segments) can be terminated by switching on the active resistor of the ProfiHub B2+R.

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 2 and 3 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 B2+R. If one PROFIBUS cable is damaged, the other cable immediately acts as a backup.

Permanent PROFIBUS diagnostics

You can switch on the diagnostic functions of the PROFIBUS communication 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.
Permanent PROFIBUS diagnostics

You can switch on the diagnostic functions of the PROFIBUS communication 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.

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 as permanent diagnostics for PROFIBUS

The ProfiHub B2+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 draw the network topology, the live-list of stations, the status of individual stations, captured outages, communication errors, communication statistics, etc.

ProfiHub provides to PROFIBUS MASTER with the following information about PROFIBUS network:

• PROFIBUS speed,
• the relay alarm contact status of the ProfiHub station,
• the presence of power at terminals 1 and 2,
• the status of the termination resistors of the individual segments,
• the 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 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.
  
  
  

An overview of the data that can be permanently read from the ProfiHub B2+R and subsequently processed in higher-level IT/IO systems.

The Combricks web page, where you can see the data about the ProfiHub B2+R device that Combricks reads and displays.

Interconnection of PROFIBUS multirepeaters ProfiHub

An example of the robust PROFIBUS architecture created by interconnecting different variants of ProfiHub multirepeaters.