USB-2-485 Interface Converter Version: 1.00 April 16th, 2006 Trinamic Motion Control GmbH & Co. KG Sternstraße 67 D - 20357 Hamburg, Germany Phone +49-40-51 48 06 - 0 FAX: +49-40-51 48 06 - 60 http://www.trinamic.
USB-2-485 Interface Converter Version Version 1.00 Date 16-Apr-06 Author GE Comment Initial version Contents 1 2 Introduction ........................................................................................................................................................... 3 The USB-2-485 Hardware .................................................................................................................................... 4 2.1 Overview.................................................
USB-2-485 Interface Converter 3 1 Introduction The USB-2-485 device is an USB to RS485 interface converter. It adds a standard 2-wire half-duplex RS485 bus interface to computers with USB interface. The USB interface of the device is USB 2.0 and USB 1.1 compatible. The RS485 interface supports all common data rates up to 3Mbit/s. No additional power supply is required as the device is powered through the USB bus.
USB-2-485 Interface Converter 2 The USB-2-485 Hardware 2.1 Overview The USB-2-485 device has two connectors, a USB type B connector for connecting the device to a PC and a 9-pin D-SUB male connector for connecting it to a 2-wire half-duplex RS485 bus. USB Type B USB Connector USB RS485 RS485 9-pin D-SUB (male) Figure 1: Overview 2.2 Connectors 2.2.1 USB The USB interface is a USB 2.0 full speed (12Mbit/s) device interface which is USB 2.0 and USB 1.1 compatible.
USB-2-485 Interface Converter 5 2.2.2 RS485 The 2-wire RS485 half-duplex interface of the USB-2-485 device supports all common data rates up to 3Mbit/s. The two differential signals are available on pin 2 and pin 7 of the 9-pin D-SUB connector of the USB-2-485 device (table 2). Pin Function 1 1 2 3 4 5 6 7 8 9 2 RS485- (RS485B) 3 GND 4 5 6 7 RS485+ (RS485A) 8 9 Table 2: RS485 9-pin D-SUB male connector, pin assignment RS485 is a multi-master bus with one master being active at a time.
USB-2-485 Interface Converter In order to support multiple-masters, the transmitter of the USB-2-485 is switched off as long as there is no transmission going on. This may lead to an undefined level on the bus in case there is no active transceiver. Therefore, in addition to the 120 Ohm termination resistor, the USB-2-485 includes an additional 1k Ohm resistor from RS485+ (RS485A) to +5V and another 1k Ohm resistor from RS485- (RS485B) to GND (Figure 2).
USB-2-485 Interface Converter 7 2.3 Technical Data 2.3.1 USB • • • Connection to USB 1.1 or USB 2.0 hosts possible (a cable is supplied with the device) USB full speed device (12MBit/s) Bus powered (no extra power supply needed) 2.3.
USB-2-485 Interface Converter 3 Software Installation The USB-2-485 is hot-pluggable. There is no need to power-off the PC while plugging in or removing the USB-2485 device. When you plug in the USB-2-485 device for the first time you will be prompted for a suitable device driver. Please note that you have to be logged in with administrator privileges in order to be able to install the device driver on Windows 2000 or Windows XP systems.
USB-2-485 Interface Converter 9 A dedicated driver for the USB-2-485 can be found on the CD (TMC Technical Library) supplied with certain versions of the USB-2-485 device or can be downloaded from our web-site (www.trinamic.com). On the CD the driver files are located in the sub-directory “\systems\USB-2-485”. Please add this path as shown below and continue: If Windows XP is configured to warn when unsigned drivers are about to be installed a warning will be displayed. Please click on “Continue Anyway”.
USB-2-485 Interface Converter After succefully installing the driver open the device manager (located in “Control panel\System”, select the “Hardware” tab and click “Device Manager”). The new device will appear as an additional COM port with the label “USB serial port”: Now, you can access your USB-2-485 device as a standard COM port. E.g. you may use the terminal program HyperTerminal supplied with Windows in order to send and receive data over the RS485 interface.
