Device Overview
The RS485 fiber-optic converter comes in a metal housing and is intended for DIN-rail mounting. The optical
interface is designed with a wavelength of 820 nm and ST connectors. The differential RS485 interface to the
terminal devices uses a 9-pole D-sub socket. Up to 31 devices can be operated on the RS485 interface. For a
point-to-point connection, the line can be terminated with a load resistor.
The auxiliary voltage is supplied via 2 terminals (N/-; L/+). The large auxiliary-voltage ranges of DC 24 V to
250 V and AC 60 V to 230 V allow the connection (without a switchover) to all popular station batteries or
alternating-voltage systems.
The following LED displays are located in the enclosure cover:
•
Error:
Error state (red LED)
•
FO Rx:
Data flow receive directions (yellow LED)
•
FO Tx:
Data flow Transmit direction (yellow LED)
•
Power On:
Auxiliary voltage (green LED)
Data Transmission
The RS485 interface is a bus-capable, 2-wire, half-duplex interface, that is, it can only receive or transmit. This
interface is thus suitable exclusively for master-slave systems having only 1 master.
As a maximum of 32 devices (including the master) listen on the RS485 bus, all bus users must be set to the
same baud rate and the same data format. The devices (slaves) must all have different device addresses.
The optical interface uses positive logic (light idle state: OFF). Arriving light is treated as active = 1 (high). To
adapt to systems that use negative logic, a switch is integrated in the converter allowing it to be set to nega-
tive logic. The optical input and the optical output of this interface is inverted at the same time in this way.
Positive logic (light idle state: OFF) is the factory setting.
In the idle state (no data transmission), the RS485 interface is in receive mode and the optical module is in
transmit mode. As a result, data arriving at the RS485 interface is sent out on the optical output.
The data direction of the RS485 interface is controlled by the optical interface via the internal logic. The data
direction of the RS485 interface switches to send when it receives a 1 bit from the optical interface. The next
time a 0 bit is received, the data bus is briefly switched to 0 and the interface switches to receive.
Protocol Transparency
The RS485 fiber-optic converter transmits in both directions transparent to the protocol. As a result, the
converter can be used for all popular asynchronous protocols from 9.6 kBd to 115 kBd (for example, IEC
protocol, DIGSI).
i
i
NOTE
The data format and the baud rate of all devices in the connected system must be the same.
1.2
Overview
1.2 Device Overview
Accessories, RS485 Optical Fiber Converter for Asynchronous Protocols Up To 115 kBd (1-Channel) 7XV5650-0CA00, Manual
11
C53000-G9050-C604-1, Edition 03.2020
