Description:

Transmission rate

The HFD-FO-MB Series Modbus fiber optic converters support all the transmission speeds between 0 ~ 115.2Kbbps.The transmission rate is set automatically as soon as the HFD receives a frame. The HFD system is a high transparent low-latency transmission system, this system in many aspects has excellent performance.The fiber-optic repeater HFD supports the any rate.

Signal regeneration
The modules regenerate the signal form and amplitude of the data received. This allows up to 200 HFD Modbus converter to be cascaded.

Segment monitoring at the RS 485 port

Each receiver monitors the RS 485 bus segment connected to it for faulty frames or continuously busy networks. If faulty frames are received by the receiver, or if the network is busy for longer than the maximum permitted send time, forwarding of the received signals is blocked until frames can be received again correctly.

Segment monitoring at the optical line

Each receiver monitors the optical line port connected to it for receive frames-and status. If faulty frames are received by the receiver, or no single for longer than the maximum permitted time, forwarding of the received signals is blocked until the port status is OK,frames can be received again correctly.

Network Topologies
The following network topologies can be realized with the HFD Modbus optical converter:

• Point-to-point topology     
• Multi-drop BUS topology
• Star topology 
• Redundant ring(DSHR)

Combinations of these basic types are also possible. Lines with two optical fibers are used to create the fiber links for these network topologies.If a malfunction – e.g. a break in a fiber line – makes a high degree of field bus network fail-safety necessary, the availability of the network can be increased using a redundant network configuration.

Line topology

In a line structure, the individual RS485 HFDs are connected together by dual-fiber optical fibers. Modules with one optical port are sufficient at the beginning and end of a line, between which modules with two optical ports are necessary.
If single point-to-point connections are to be built up, this can be achieved using two modules each with one optical port.

Star topology

Several modules are combined to form an active RS485 star coupler. Other modules are connected to this by dual-fiber optical fiber lines. The modules of the star coupler are connected to
one another via the electrical port(electrical star segment). All HFD types for different fiber types can be combined using the electrical star segment.
Modules with one or two optical ports can be used to create an active RS485 star coupler. Modules with one optical port are sufficient for connecting a terminal or an RS 485 bus segment to the active star coupler.

Redundant optical ring

This network topology represents a special form of line topology. A high degree of network operating safety is achieved by ”closing“ the optical line. A redundant optical ring can only be realized with modules with two optical ports of the same type.
An interruption of one or both optical fibers between two modules is detected by the HFD and the ring is transformed into an optical line.If one module fails only those terminals connected to this module or the RS 485 segment are uncoupled from the ring. The remainder of the network itself continues to function as a line. The error is indicated by the LEDs on the two HFD connected to the malfunctioning optical fiber and their signaling contacts. The segmentation is lifted automatically as soon as both modules recognize that the segmented field bus network is functioning correctly with the test frames.

Model Selection: