Due to the ease of setup and cost saving features, there are plenty of asynchronous serial devices widely used in industrial systems around the world. However, the longer the transmission distance, the more data corruption due to the capacitive reactance, inductive reactance and impedance characteristics of the cable, as well as signal reflection caused by impedance mismatch and impedance discontinuity. Fiber connections provide the benefits of noise immunity and transmission distance. Therefore, serial-to-fiber optic converter(also called serial-to-fiber optic modem) is the best solution to overcome these problems and extend the reach of your serial communications. The MODEL277 from 3onedata is a series of industrial serial-to-fiber optic converters that transfer RS-232/RS-422/RS-485 signals to optical fiber ports to enhance transmission distance.
Extend Transmission Distance for P2P Serial Inter-communication
The MODEL277 series from 3onedata is equipped with one RS-232, RS-485/422 or 3IN1 serial port and one ST/FC/SC fiber port that extend serial transmission up to 120km with single-mode or up to 2km with multi-mode. The serial-to-fiber converters are typically used in pairs, any two remote pieces of asynchronous serial equipment can communicate over fibers with a pair of 3onedata’s MODEL277 serial-to-fiber converters.
The plug-and-play design makes the MODEL277 series easy to deploy in any applications, it can transmit data immediately once it connected, field engineers only need to master some knowledge of serial bus. In addition, it adopts low-power design (no load:0.35W@12VDC, full load: ＜0.7W@12VDC), it can be powered by UPS or storage battery when field power do not meet requirements.
Unlike most unmanaged devices, the MODEL277 series abandons the cumbersome DIP switches in traditional design. Once the serial data from the terminal is received, the MODEL277 series can recognize and adapt to the corresponding baud rate. If the data transmission direction is reversed, MODEL277 can also adjust the data transmission direction spontaneously through ADDC (Automatic Data Direction Control) technology to ensure reliable data transmission.
1. Fire Control System
The fire control system is generally divided into two levels: the field level and the center level. The field fire alarm controller is generally connected and monitored in real time by environmental sensing equipment such as smoke alarms and temperature sensors in key areas to detect in real time whether there is abnormal situation, and report the monitoring data to central fire alarm controller in real time. Once an abnormal situation occurs, the sound and light alarm connected to the field fire alarm controller will issue an alarm to remind the field engineer to activate the gas fire-extinguishing device, the central fire alarm controller can also remotely control the gas extinguishing device to extinguish the fire after getting the real-time alarm information.
In order to realize the interconnection between the fire alarm controllers, controllers generally reserve communication interfaces such as CAN or RS-485 for external communication, but the communication distance of these types of interfaces is generally only 500-800m at a baud rate of about 100K. However, central alarm controller is generally located dozens of kilometers away. To break the transmission barrier between serial terminals, the MODEL277 series came into being.
MODEL277B is a transparent transmission serial-to-fiber modem that can provide users with RS-485/422 serial ports and special optical ports (It can only be interconnected with the fiber port of MODEL277 series). MODEL277B can automatically detect the signal rate without jumper or DIP setting, and self-forward with zero delay. MODEL277 is a P2P type (used in pairs) MODEM, its optical port supports a maximum transmission distance of 120KM, which can effectively extend the communication distance of the RS-485/422 serial port, thereby ensuring effective communication between fire alarm controllers.
2. Railway PSCADA System
Railway PSCADA system is divided into power dispatching system and substation integrated automation system. Among them, the integrated automation system of the substation not only has the functions of equipment monitoring, data collection, time sequence recording, etc., but also undertakes the functions of information processing, dispatching communication, central signal, and protection automation of the entire substation.
On the one hand, the PSCADA system needs 7*24 uninterrupted collection of the operation status of the power facilities in the jurisdiction. At the same time, when engineers visit the power supply area, power on and power off the high-voltage lines under the jurisdiction is also required to ensure the personal safety of the engineers. In most cases, the field grid controller only has serial ports such as RS-485 for connecting with the main controller and data acquisition device of the monitoring center. However, the railway site is often dozens of kilometers away from the monitoring center, and the RS-485 interface cannot meet the communication needs of more than 1.2KM. In this case, railway operators often choose to use multiple pairs of MODEL277 to extend the long-distance communication between the control and acquisition device of the monitoring center and the serial port of the field grid controllers.
The distributed photovoltaic power station monitoring platform is mainly used in solar power stations with scattered installation sites, which can realize unified monitoring and management of scattered power stations. It can monitor and collect the operating data of photovoltaic substations, and transmit the data back to the database server of the monitoring center for data monitoring, query, summary, analysis, management and display.
The monitoring platform needs to be connected to the IP network, so the photovoltaic measurement and control devices of the photovoltaic substation are mostly connected to the serial device server, and establish communication with the database server through TCP socket, so as to realize the serial connection to the network. For photovoltaic measurement and control devices with short distance, the serial server can be directly connected to them through an RS-232 or RS-485 serial port; but for photovoltaic measurement and control devices with long distance, engineers generally use MODEL277 to convert serial electrical signals into serial optical signals, transmit data back to the central room through optical cables, and then connect with serial device server, which not only breaks the limitation on the transmission distance of the serial port signal, but also improves the stability of data transmission.
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Headquartered in Shenzhen, founded in 2001, 3onedata has been dedicated to IIoT for 21 years, with rich professional experience of providing industrial communication solution and service for partners and customers worldwide. In 2020, 3onedata became the first IIoT company to be listed on Shanghai Stock Exchange (SSE) STAR Market, a milestone for our sustainable growth and development.
Innovation, Value and Honor are 3onedata’s core values, which guide our business strategy and operation. 3onedata attaches great importance to the overall development of the company, with continuous annual investments to ensure innovation in production, R&D and marketing in order to provide more competitive products in the market and support the success of our customers. Total Service System(TSS) is our unique operation model, providing the customer a feeling and experience of total service, which will lead to long-term effective development of 3onedata. From our persistent core values and competence in delivering great performance, we are confident in facing the uncertain future. 3onedata are looking forward to cooperating with you, for mutual benefits, and move forward together, on the way.
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