Two Ways of RS485 to Fiber Optic

Published Time: 2016-04-24 Author: Shanghai ZLAN Views: 11250

As an advanced communication medium, optical fiber has the advantages of long communication distance, low error rate and strong anti-interference ability. So when you need to connect the RS485 devices that are very far away, you often need to convert the RS485 signal into a fiber optic signal. The serial port of this article takes RS485 as an example, but it can also cover the serial ports such as RS232/422.

There are two types of optical fiber, namely the protocol type and the level type, respectively to ZLAN9153 and ZLAN9163.
1) Protocol type: also known as the optical fiber serial device server, it converts the serial port data into TCP data and requires the transformation of communication data format. The advantage is that it can be transmitted through the optical switch, which can share a fiber with other devices. The upper computer accesses the IP address of ZLAN9153 directly through the Ethernet port and obtains the data. However, if you want to pair-connect 2 RS485 devices you first need to know the serial parameters of RS485, including baud rate, data bits, check bits, stop bits and so on, you need to carry out network pair-connection IP configuration. The configuration is more complex.
2) Level type: directly convert RS485 signal into optical fiber signal, only the transmission medium change, data format has not changed. The advantages are suitable for the RS485 device pair-connection, without knowing the serial parameters and network pair-connection configuration. It must be a pair of ZLAN9163 devices alone with a single fiber, and the computer can't direct access to data via IP, if want to obtain data they should be used in pairs, the computer connect through the serial port on the other end.

The use presentations of ZLAN9153 and ZLAN9163 are shown in figure 1 and figure 2 respectively.

ZLAN9153 fiber serial device server is generally used for single use. It can be connected to optical fiber switch. The upper computer monitoring software can access the IP address of ZLAN9153 directly to obtain the data. This way ZLAN9163 is impossible to achieve. ZLAN9153 actually converts RS485/232 data into TCP format, which is a serial device server, but is transmitted on optical fiber. When connecting ZLAN9153 to the optical switch, pay attention to the A end connection of the switch ZLAN9153-5 (B end); B end connection ZLAN9153-3 (A).

ZLAN9163 is generally used for fiber optic pair-connection, and the two RS485 devices are connected by optical fiber. There is no need to configure parameters such as serial port rate and 9163 IP, which can be plug and play. At this point, ZLAN9163 can be regarded as a pure RS485/232 to optical fiber communication medium converter.

In some cases, even for pair-use, ZLAN9153 is recommended. At this point you must know serial port parameters (baud rate, stop bits, parity, data bits) of the device, in addition, need to configure two ZLAN9153 in pair-connection mode, that is, one as Client one as Server. ZLAN9153 is recommended as follows:
1) There is no single optical fiber left for 485 optical fiber use, or a number of 485 host-slave systems need to pair-connection through a fiber, at this time, use ZLAN9153 pair-connection cooperating with optical switch to realize.
2) Field network is the structure of optical switch, which requires cross-gateway and cross-routing.
3) The host is a computer, and the computer wants to access the device through the network, not the serial port card, USB to serial port, etc.