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3-way communication for serial-to-fiber converters
Most serial-to-fiber converters on the market today only provide one serial port and one fiber port for physical layer media conversion. But as industrial networking applications increase in complexity, additional capabilities and features including easy wiring, system diagnostics, and dual hosts/slaves are becoming more important. Selecting a media converter with 3-way communication offers the best solution to address these concerns. |
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How does 3-way communication work?
Let us use the ICF-1150 series media converters to illustrate how 3-way communication works for serial-to-fiber converters. Each ICF-1150 is equipped with one fiber port and two serial ports. The D-sub connector is used for RS-232 communication and the removable terminal block is used for RS-422 or RS-485 communication. When the ICF-1150 series converter receives data through one of its ports, it will send the data back out through the remaining 2 ports. For example, when the ICF-1150 series receives a command from the remote device via the fiber port, it will convert the command and transmit it via the RS-232 port and RS-422/485 port at the same time.
Easy wiring
Compared to traditional serial-to-fiber converters that only have one serial port and one fiber port, Moxa's ICF-1150 series provides 3 ports for data communication. Based on our many years of experience, we have selected the most common connectors used in the industry, such as D-sub for RS-232 connections, and removable terminal blocks for RS-422/485 connections. Adopting commonly used connectors can save users a great deal of time in the field installation and maintenance.
Easy system diagnostics
When connecting PLCs or meters to a fiber converter, users need a clear way to diagnose what is wrong if the send/receive data are blocked, stopped, or an error occurs. In most cases, users will change the wiring to see if the failure was caused by improper wiring. Users may also try using a USB-to-serial converter to connect the converter to a laptop that can run diagnostics. After checking the data transmission, users remove the USB-to-serial converter and reconnect all the wires. However, none of that can guarantee that the new wiring is correct.
Three-way communication can solve this problem. Consider the following scenarios:
- A. Connecting an RS-485 device to fiber converter.
Since the RS-232 port on the fiber converter is still unused, we can connect the RS-232 port to a laptop and open the COM port by “Hyper Terminal” to see what data is running. After running diagnostics and correcting the wiring (if needed), we can remove the link between the laptop and converter without affecting any running systems.
- B. Connecting an RS-232 device to a fiber converter
We can use a USB converter such as Moxa's UPort 1130 or UPort 1150 to provide a computer with direct access to RS-485 data. Again, after checking the data and correcting the wiring (if needed), we can remove the link between the laptop and converter without affecting any running systems.
Dual hosts/clients, redundant solution, and data logging
Since the 3 ports are virtually connected, you can only connect a maximum of 2 serial ports to different devices. For example, users can connect 2 master devices, such as PLCs, one at the RS-232 side and another on the remote side via fiber link. The slave device can be connected to the RS-485 port and receive the command from a local master or remote master. A computer can also be used to monitor the system and check all running communications as a solution for data logging.
Limitations
Since the 3 ports are virtually connected, the converter will not receive data from more than two devices. Connecting more than two devices will cause the program to halt or disrupt data transmission since two devices sending data at the same time will cause you to receive incorrect and unexpected data.
Despite these limitations, 3-way communication remains a powerful tool that is definitely worth considering when you are in the market for a new serial-to-fiber media converter.
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