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select) to the virtual COM port, the communication with RS232 device will be realized, i.e. the
conversion process from virtual COM port driver program to calling USB driver program is
completely transparent for users, and users need not pay attention to realization details of the
process and nothing remains but to consider the serial port communication.
2： Description of USB485× product
USB485× is an industrial control intelligent converter of USB to RS-485/422 and it is the
best solution for you to realize communication with RS-485/422 device by means of USB.
Compared with ordinary RS-232 RS-485/422 converter, USB485× converter has the
advantages below:
Generally, the method of controlling RS-485/422 device by means of computer is to connect
a converter of RS-232 to RS-485/422 by means of RS-232 serial interface of computer for data
communication. In this mode, application program realizes communication with RS-485/422
device by visiting COM port of computer, but this mode now has some problems below:
(1) RS-232 is a relatively out-of-date communication protocol and many new computers, e.g.
notebook computers, have had no the interface;
(2) The speed rate of RS-232 is not high enough (high-speed RS-485 can realize 10Mbps
communication rate, and generally, the baud rate of RS-232 port of computer can
reach115kbps only, so it fails to meet the requirement of conversion rate);
(3) The passive (without external power supply) converter of RS-232 to RS-485/422 is
required to be used in many places, and here the converter must be powered from RS-232
port for normal working, it probably suffers from a power shortage.
While USBRS-485/422 converter covers the above shortage.
(1) USB (universal serial bus) is current prevailing computer interface standard. Many new
computers all have USB interfaces;
(2) Compared with RS-232, USB interface has higher communication rate. USB1.1 can reach
12Mbps and USB2.0 can reach 480Mbps, and moreover, multiple rates and
communication modes are available, so the requirement of conversion to high speed 485
can be met fully.
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