This converter provides two ways serial communications signal conversion between the RS485 to and from a personal computer USB port using virtual serial COM port. Using the USB-RS485 module, one can connect up to 32 RS-485 devices simultaneously to a single USB port. Typically it is used for multi-drop communication.

To check if your RS232 to RS485 converter (or USB to RS485 converter) is working properly you can make a loop-back test using a terminal program such as AccessPort. This way you can determine if the converter can send and receive characters properly.

Determining What COM Port a USB to RS-485 Converter is Using

1. Open the Start Menu by clicking the Windows logo button.
2. Click Control Panel.
3. Click System.
4. Click Device Manager.
5. Click the arrow next to Ports to expand the list.
6. Find the USB Serial Port and make note of the COM number listed with it.

RS-485 is a duplex communication system in which multiple devices on the same bus can communicate in both directions. UART having dedicated transmit and receive lines allows it to operate as full-duplex, half-duplex, or even simplex, which means data only ever goes out or comes in on one line.

The USB-RS485 is a fully automatic plug-and-play USB module that connects to your PC via the Universal Serial Bus (USB) port and provides robust USB to RS-485 protocol conversion with automatic RS-485 flow control.

RS232 is more than able to perform for a short distance and low data speed requirements. RS232 has a transmission speed of 1Mb/s up to 15M. However, RS485 has a data transmission speed of up to 10Mb/s for a distance of 15M. At the maximum of 1200M, RS485 transmits at 100Kb/s.

Standard RS485 transceivers operate over a limited common mode voltage range that extends from –7V to 12V. In a commercial or industrial environment, ground faults, noise, and other electrical interference can induce common mode voltages that exceed these limits.

This way you can determine if the converter can send and receive characters properly. If you have a RS485 converter without an ‘Echo On’ option, you will need a second RS485 port or converter to receive the signal transmitted by the first converter OR to transmit a signal to be received by the first converter.

MODUS specifies both a primitive query and response syntax and a channel specification being TCP or RS485. Most devices these days are connected via ethernet, and so MODBUS-TCP is probably more prevalent. However there are still times when you might USB-RS485 need to connect to or test a MODBUS device with RS485.

It has a simple user interface that can be used to control, monitor, test, and debug RS232/RS485/RS422/TTL/Ethernet/Fiber Optic data utilizing our serial products for serial data conversion. Although AccessPort is an advanced serial port terminal / monitoring tool with robust functionality while easy to use due to its simplistic user interface.

FTDI VCP driver installed. This is the driver for the USB<>485 converter and it can be downloaded here. Supermodified Commander installed. This is the stand alone application that communicates to the controllers. It can be downloaded here.