Serial Interfaces
for RS-485 and RS-232
PCI, PXI/CompactPCI, PCMCIA, and ISA Interfaces
Compatible with standard PC serial port PCI-232, PXI-8420, PXI-8422,
Full Windows 2000/9x Plug and Play
compatibility for switchless
configuration
PCMCIA-232, AT-232
RS-232 interfaces
Cable lengths to 15.6 m (50 ft)
2, 4, 8, and 16 ports
Handle RTS/CTS hardware
handshake lines
460 kb/s maximum transfer rate
Transmit and receive FIFOs up to
64 bytes
Note: Features vary depending
on board model. See detailed
specifications.
Driver Software
NI-Serial for
Windows 2000/NT/Me/9x
Interrupt-sharing between ports
2000 V isolation
PCI-485, PXI-8421, PXI-8423,
PCMCIA-485, AT-485
Application Software
LabVIEW
Measurement Studio
Lookout
C/C++
Visual Basic
RS-485 or RS-422 interfaces
Communicates with up to 31 devices
Automatic transceiver-control mode
for 2-wire RS-485 devices
Cable lengths to 1.2 km (4000 ft)
Any package written to the Microsoft
serial driver interface
Overview
Cabling
EXPRESS
CODES
Th e Nation al In stru men ts serial in terface board s for PCI,
Our 2 and 4-port serial devices are not
PXI/CompactPCI, PCMCIA, and ISA are asynchronous serial interfaces shipped with serial interface cables. Two-
for communicating with serial devices. Depending on the platform, port versions use DB-9 male connectors
interfaces are available with up to 16 ports and full Windows 2000/9x with standard pin assignments for RS-485
Plug and Play compatibility, which gives you the benefit of automatic and RS-232 connectors (see Figure 1).
configuration for easier installation and maintenance. You can install Four-port devices use 10-position modular
For information or to
buy products online,
visit ni.com/catalog
and enter:
pxi8420
at232
and use these boards as standard serial ports from your existing
applications. Development environments such as Visual Basic, Visual
C++, and Excel, as well as our LabVIEW, 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, reliable interrupt
sharing between ports, and access to the advanced transceiver
control mode of the RS-485 interface devices.
phone jacks, so all four connectors can
at485
pci232
pci485
pcmcia232
pcmcia485
Pin 5
Pin 1
Pin 9
Pin 6
Figure 1. DB-9 Connector Pin Locations
Isolation
exist on a single back panel (see Figure 2). When purchasing a 4-port
A common problem in many industrial applications is ground loops – serial device, you must order cables that convert the phone jacks to
current flowing through the ground line when ground voltage levels either DB-9 or DB-25 male connectors with standard pin assignments.
differ between connected devices. On RS-485, this problem results in
In general, you should order four converter cables per 4-port serial
a common-mode voltage produced by the difference in ground levels device. Note that a converter cable is not designed to go the full
or by noise induced on both lines. Isolation of serial ports eliminates distance from a 4-port serial interface directly to your instruments. Our
this problem and protects the computer system in harsh industrial most popular converter cables convert the 10-pin phone jack on a
environments. The National Instruments PCI, PXI/ CompactPCI,
Pin 1
Pin 10
PCMCIA , and AT serial devices are available with optical isolation up
to 2000 V for such applications.
Figure 2. 10-Position Modular Jack Pin Locations
National Instruments 821
Tel: (512) 794-0100 • Fax: (512) 683-9300 • info@ni.com • ni.com