The FOC11… fiber optic media converter converts RS485 signals, e.g. from PROFIBUS-DP

or Modbus RTU, on copper cables into optical

signals and vice versa. Bus signals from the

safe area up to zone 1 can thus be transmitted intrinsically safe, potential-free and interference-free over long distances.

The 1-channel FOC11… has a Sub-D male

connector and a fiber optic port with ST connector. Two converters are always required to

build an optical line.

The functionality of the media converter is set

via a 10-pin rotary coding switch:

■ Pos. 0 Profibus-DP segment coupler

■ Pos. 3…9 Modbus RTU segment coupler

Transmission rates of 9.6 kbps up to 1.5 Mbps

are possible and will be automatically detected in Profibus-DP mode. When using the

Modbus RTU protocol, the transmission rate is

selected via positions 3…9 of the rotary coding switch.

When using an OM1 fiber optic cable

(62.5/125 μm), the minimum transmission

range is 2500 m, and for OM2 (50/125 μm),

the minimum transmission range is 1500 m.

The signal amplitude, edge steepness and

bit width (byte refresh) are processed during

the transmission of Profibus-DP, Modbus RTU

and byte-oriented serial data telegrams. In

addition, the validity of the Profibus-DP telegrams is checked against the start delimiter

when the telegrams are received. In this way,

faulty Profibus telegrams are not transferred

to the next segment.

For diagnostic purposes, three status LEDs

(power supply, fiber optic segments, RS485

segment and detection of the transmission

rate in the RS485 segment) as well as an

alarm output are available.

The series of fiber optic media converters consists of a total of four converters, which differ

in the number of fiber optic ports, the RS485

signals and the installation location.

■ FOC11-3G, 1-channel

■ FOC11EX-2G, 1-channel

■ FOC12-3G, 2-channel

■ FOC12Ex-2G, 2-channel

The 3G versions can be installed in Zone 2

and have a standard RS485 interface. The

2G versions with intrinsically safe RS485 interfaces may be installed in Zone 1. In all versions, the fiber optic interface is intrinsically

safe, so that all converters can interconnect.

Equipotential bonding is implemented with

a threaded bolt that is only connected to the

housing. The shielding of the Fieldbus cable

is implemented via a separate connection with

the option of choosing between capacitive or

direct grounding. The housing potential is not

connected with the shielding potential.

■ Media converter for Profibus-DP, Modbus

RTU and byte-oriented serial data telegrams

■ Automatic detection of the transmission

rate

■ Transmission length up to 2.5 km

■ Wire-break monitoring

■ Intrinsically safe fiber optic interface

■ RS485 interface

■ Mounting in zone 2 allowed