Serial Interfaces for PXI, PCI,
PCMCIA, Ethernet, USB, and ISA
NI Serial Interfaces
• Flexible baud rates from
57 b/s to 2 Mb/s (NI 843x)
• Up to 128 B transmit/receive
FIFOs (NI 843x, USB, ENET)
• Full multiprocessor and
hyperthreading compatibility
(NI 843x)
• Memory-mapped to prevent
I/O resource conflicts (NI 843x)
• 3.3 and 5 V PCI slot-compatible
(NI 843x)
• NI-Serial device driver works with
NI-VISA for easy development
• LabVIEW Real-Time compatibility
for deterministic control
(Plug-In, ENET)
• Optical isolation up to 2000 V (plug-in)
Operating Systems
• Windows 2000/XP (NI 843x, USB)
• Windows 2000/NT/XP/Me/9x
(PXI, PCI, PCMCIA, ISA)
• Windows 2000/NT/XP (ENET)
NEW
Recommended Software
• LabVIEW
• LabWindows/CVI
• Measurement Studio
Other Compatible Software
• C/C++
• Visual Basic
• Any package that uses the
Microsoft Win32 Serial API
Driver Software (included)
• NI-Serial
Overview
National Instruments offers serial interfaces for PCI, PXI, PCMCIA,
ISA, USB, and Ethernet. They are asynchronous interfaces for
communicating with instruments via serial ports. Depending on the
platform, interfaces are available with up to 16 ports and full
Windows 2000/NT/XP/Me/9x plug-and-play compatibility, which
gives you the benefit of automatic configuration for easier
installation and maintenance. You can install and use these devices as
standard serial ports from your existing applications or with
applications written with NI-VISA. Development environments such
as Visual Basic, Visual C++, and Excel, as well as NI LabVIEW,
LabWindows/CVI, Measurement Studio, and Lookout application
software products, can access the add-in serial ports using standard
serial I/O functions. All interface devices include an enhanced serial
driver for improved performance, easy configuration, and access to
the advanced transceiver control modes of the RS485 interfaces.
Cabling
NI 2-port serial interfaces have DB-9 male connectors with standard
pin assignments for RS485 and RS232 connectors (see Figure 1). The
4-port interfaces use 10-position modular phone jacks, so all four
connectors can exist on a single back panel (see Figure 2). When
purchasing a 4-port serial interface, you can order cables that convert
the phone jacks to either DB-9 or DB-25 male connectors with
standard pin assignments. In general, you should order four
converter cables per 4-port serial device. Note that a converter cable
is not designed to go the full distance from a 4-port serial interface
directly to your instruments. Our most popular converter cables
convert the 10-pin phone jack on a 4-port device to the same
DB-9 male connector found on a typical PC serial port. The
connection from this converter to your serial device uses the
standard cables used with the PC serial port.
National Instruments ships cables with all isolated ISA and
PCI 4-channel serial boards to ensure isolation. NI 4-channel PXI
serial modules, which do not require special isolated cables to ensure
isolation, come without cables.
All 8-port serial interfaces include an adapter cable that connects
to the SCSI 68-pin connector on the device and terminates in eight
standard DB-9 male connectors (see Figure 3).
All 16-port RS232 serial interfaces include a breakout box that
connects to the SCSI 100-pin connector on the device and terminates
in 16 standard DB-9 male connectors (see Figure 4).
NI ships PCMCIA serial cards with interface cables that provide
one, two, or four DB-9 male connectors. These DB-9 male
connectors provide standard pin assignments for RS485 and RS232
connections. Note that these cables are not designed to go the full
distance from a PCMCIA serial card to your instrument. The cables
provide the same DB-9 male connectors found on a typical PC serial port.
Isolation
Ground loops – current flowing through the ground line when ground
voltage levels differ between connected devices – are a common
problem in many industrial applications. On RS485, this problem
results in a common-mode voltage produced by the difference in
ground levels or by noise induced on both lines. Isolating serial ports
eliminates this problem and protects the computer system in harsh
industrial environments. The National Instruments PCI, PXI, and AT
serial interfaces are available with optical isolation up to 2,000 V for
such applications.
NI [ NATIONAL INSTRUMENTS CORPORATION ]
