RS-422/485 Serial Communication Card
- Universal PCI, PCI-X, 3.3V and 5V compatible (Call for PCI-Express availability)
- Supports RS-422 and RS-485 protocols
- Automatic control of RS-485 driver under all operating systems
- Includes type 16550 UART with 16-byte FIFO buffers
- Baud rates up to 460,800 baud
- Detected as standard COM port by all operating systems
- No base address or IRQ switches to set
- Meets MD1 PCI Low Profile Specification
- RoHS Available. Please contact us for ordering information
- Support for Wind River VxWorks (call for ordering information)
The card supports RS-422 and RS-485 balanced-mode transmission/reception. Each card has capability to add bias voltage. (RS-485 communication requires that one transmitter in the network must supply a bias voltage to ensure a known 'zero' state when all transmitters are OFF). Also, receiver inputs at each end of the network should be terminated to eliminate ringing. The card supports these options by means of jumpers on the card.
Type 16550 UARTs are used as the asynchronous communication elements. These include a 16-byte transmit/receive FIFO buffer to protect against lost data in multi-tasking systems while maintaining 100 percent compatibility with the original IBM serial port.
A crystal oscillator is located on the card and permits precise baud rate capability up to 115,200 baud. Higher baud rates, up to 460,800 baud, are achieved by changing a jumper on the card. The driver/receivers used, type 75176, are capable of driving extremely long communication lines at high baud rates. They can drive up to ±60 mA on balanced lines and receive inputs as low as 200 mV differential signal superimposed on common mode noise of +12V to -7V. In case of communication conflict, the driver/receivers feature thermal shutdown.
When the card is first installed, the operating system will detect it as new hardware and assign it an IRQ number and base address. There are no switches to set or base addresses to assign, making it easy to use. From this point on, the card behaves as a standard COM port.
RTS and AUTO TRANSCEIVER CONTROLIn RS-485 communications the driver must be enabled when needed and then disabled to permit all cards on the network to share a two-wire or four-wire cable. The card has two methods to control the driver: automatic (AUTO) and request-to-send (RTS) control. Under automatic control, the driver is enabled (and the receiver disabled) when data are ready to be transmitted. When transmission is complete, the driver remains enabled for the transmission time of one additional character and then is disabled. The card automatically adjusts its timing to the baud rate of the data. (NOTE: For use in half-duplex mode under Windows, the card must be operated in the AUTO mode.) In the RTS mode, application software must set a bit to enable the driver and reset that bit to disable the driver.
Drivers and Downloads
Information about our Free Software packages:
ACCES is proud to provide a full suite of software support with every Data Acquisition product. We are committed to supporting the most popular operating systems and platforms for our customers. Currently we are actively supporting Windows XP through Windows 10, including "Server 2008," "Embedded," and "Compact" flavors in both 32-bit and 64-bit for all plug-and-play products including PCI, PCI Express, USB, and more. Many products continue to ship with support for additional operating systems such as DOS, Windows 95, 98, Me, NT4, and 2000.
Among the software we deliver with our products are sample programs in a wide variety of programming languages. These samples are used to demonstrate the software interfaces to our products — and many can be used as-is in your production environments, or to test functionality of the devices out-of-the-box. We're currently actively supporting sample programs in Visual C# and Delphi with many devices including samples in Visual Basic and Visual C/C++, as well as Borland C/C++ 3.1 for DOS. Additionally we provide National Instruments LabVIEW compatible DLLs and demonstration VIs for many of our devices.
Drivers for various operating systems are also provided, including active support for Windows XP -> 10 — all in both 32-bit and 64-bit flavors, and including consumer, server, and embedded varieties — as well as the Linux kernels 2.6 and newer and recent macOS versions. Many products continue to ship with driver support for Windows 95, 98, Me, NT4, and Windows 2000, but support for these operating systems is considered deprecated.
Setup Programs and Utilites
Our Data Acquisition devices also include a graphical setup utility that walks you through the process of configuring any option jumpers or switches on the device, as well as explaining a little about the various connectors present.
Many devices also include utility programs - little tools to make your use of the device easier, such as WinRISC, a "Really Incredibly Simple Communications" terminal program that lets you get started instantly with serial devices.
"Register Level" Documentation
Besides all this software in all these languages and operating systems ACCES has a policy of open and transparent development: none of our lowest-level "register" interfaces are hidden from you — we document every register in every bus card, every command in every serial board, and every usb control transfer in every USB Data Acquisition board. These lowest-level interfaces allow you to develop for our products in ANY operating system or language, regardless of our actively supporting it or having a driver for it. We have customers actively developing in ADA, Android, Python, Java, MATLAB, Solaris, and more, just by referring to our complete low-level interface documentation! And we provide the full source code to all of our drivers, regardless of operating system, to give you an even bigger head start in your own development tasks.
No Fees or Royalties
All of this software is provided at no additional charge, and is licensed under any of a variety of flexible — and royalty free — options. Check out our software license explanation if you'd like more information.
ACCES also offers Custom Software Services for our products. Our prices are unbelievably low, often as inexpensive as free! If you need something tweaked to support your needs, or an entire enterprise application developed from scratch, it is definitely worth your time to inquire with us, first.
Further information about available ACCES Software:
- Redistributing Windows Drivers
- A list of ACCES drivers and the files that compose them under different versions of Windows, so you can easily redistribute ACCES cards and drivers.