![background image](http://html.mh-extra.com/html/national-instruments/enet-232-series/enet-232-series_manual_708976112.webp)
USB-485 Programmatically Controlled Bias
Resistors
On the USB-485 hardware, there are programmatically controlled
onboard bias resistors. In addition, the USB-485 two and four-port
hardware has user-configurable socketed bias resistors. By default, the
USB-485 hardware uses the programmatically controlled bias resistors,
which are connected to the receive signals of each port to maintain a
known state when the bus is idle. The connections are made as follows:
RXD+ and CTS– are pulled up to +3.3 V
RXD– and CTS+ are pulled down to GND
The follwing figure shows a USB transmission line using bias resistors.
USB-485 Transmission Line Using Bias Resistors
The values of the programmatically controlled bias resistors have been
calculated such that there is a voltage of at least 200 mV between the
differential pair. Rather than using the programmatically controlled bias
resistors, you can load custom values of resistors into the sockets in front
of each connector or use external bias resistors. If these resistors are
installed, make sure the programmatically controlled bias resistors are
disabled.
Note
Using custom bias resistors on the USB-485 two port may
violate the USB suspend current specification.
Note
The series 25 resistors in the figure above are for short-
circuit protection and do not impact serial communication.
Содержание ENET-232 Series
Страница 1: ......
Страница 5: ...Using Help Conventions Navigating Help Searching Help Printing Help File Topics ...
Страница 17: ...How to Use this Help File To use this help file refer to the following flow chart and the appropriate topics ...
Страница 21: ...Serial Hardware Overview PCI Kits PXI Kits USB Kits ENET Kits ExpressCard Kits PCMCIA Kits ...
Страница 24: ...PCI 485I RS 485 two port isolated RS 485 four port isolated ...
Страница 27: ...PXI 8423 RS 485 two port isolated RS 485 four port isolated ...
Страница 63: ...Save Pending Changes To save your changes to this item click Save ...
Страница 65: ...Restore Defaults To reset the fields to their default values at any time click the Defaults button ...
Страница 98: ...0 LPVOID l_SerialInterface sizeof l_SerialInterface LPDWORD l_ByteCount NULL ...
Страница 127: ...2 PORT LEDs USB Serial Hardware LEDs ...
Страница 139: ...Connecting the Cables to a Four Port PXI Serial Board ...
Страница 141: ...67 58 50 41 33 24 16 7 TXD 9 RI 9 ...
Страница 167: ......
Страница 169: ......
Страница 171: ......
Страница 181: ...How many serial ports can I have on my machine You can have up to 256 serial ports ...
Страница 189: ...nslookup hostname If you still cannot communicate with your device contact National Instruments ...
Страница 201: ...Glossary Prefixes Symbols A B C D E F G H I K L M P R S T U V ...
Страница 203: ...Symbols degrees ohms percent ...
Страница 204: ...A A amperes ANSI American National Standards Institute ...
Страница 205: ...B b bits B bytes baud bits per second bps bits per second ...
Страница 206: ...C C Celsius COM Computer Output Microform used in reference to a communication port CTS clear to send ...
Страница 208: ...E EIA Electronic Industries Association EMI electromagnetic interference ENET Ethernet ...
Страница 209: ...F FCC Federal Communications Commission FIFO First In First Out ft feet ...
Страница 210: ...G G ground ...
Страница 211: ...H HSI handshake input HSO handshake output Hz Hertz ...
Страница 213: ...K Kbaud kilobits per second ...
Страница 214: ...L LED light emitting diode ...
Страница 215: ...M m meters MB megabyte ...
Страница 216: ...P PC personal computer PCI Peripheral Components Interconnect ...
Страница 218: ...S s seconds SCSI Small Computer Systems Interface ...
Страница 220: ...U UART Universal Asynchronous Receiver Transmitter ...
Страница 221: ...V V volts VDC volts direct current VXI VME eXtensions for Instrumentation ...
Страница 222: ...Important Information Warranty Copyright Trademarks Patents Warning Regarding Use of NI Products Compliance ...