Industrial communication USB serial port signal

author: Echo
At present, the USB interface of the computer has been widely used. Generally, each computer has multiple USB ports. When the communication distance of USB exceeds several tens of meters, it is impossible to use the cable connection scheme or even the wireless scheme. At present, only optical fiber can realize the long-distance communication of USB.

The USB port has become the most important external interface of the computer and can replace almost all external interfaces. The USB specification stipulates that the USB communication distance is up to 5 meters (connected with USB-HUB). There is also a USB remote extender with RJ-45 cable on the market, which is said to be up to 50 meters. The farther USB communication can only be realized by optical fiber at present: the maximum distance of multimode fiber is 4Km, and the maximum distance of single-mode fiber is 40Km.

First of all, if you know the versatility of USB, you will understand the importance of USB. Queue up several common external interfaces according to the versatility of use: USB≥Ethernet port>serial port>PS/2, printing port, etc. The USB port can easily convert the Ethernet port, serial port, PS/2 port, printing port, and even audio and video ports. Conversely, serial ports, PS/2 ports, printing ports, etc. cannot generate USB ports, because the USB specification is more complicated. Only the Ethernet port and power supply can generate the USB port, and special software support is required. Of course, the internal bus interface of the computer is universal: the PCI port of the desktop computer and the PCMCIA port of the notebook can generate a USB port, and no driver is required.

In some industrial communication occasions, due to the small amount of data and the special requirement of real-time, serial communication is often used, and the communication protocol is RS-232 or RS-485. The USB port of the industrial computer can carry out serial communication with RS-232 or RS-485 protocol through optical fiber. At this time, you can choose a USB/serial fiber converter. Since the OPTU232L1 (or OPTU232SL1) still transmits serial signals, it must be used in pairs or paired with other serial port/fiber converters from Boss. Due to the use of optical fiber as the communication transmission medium, it has the advantages of isolation of high voltage, anti-electromagnetic interference, and long transmission distance.