FEATURES
Universal PCI, PCI-X, 3.3V and 5V compatible
Four-port
serial communications card for PCI bus
Supports
RS-485 multidrop networks
Includes
type 16550 UART with 16-byte FIFO buffers
Baud rates
up to 460,800 baud
Automatic
control of RS-485 driver under Windows sytems
Choice
of I/O connection methods
No base
address or IRQ switches to set
FUNCTIONAL
DESCRIPTION
The
PCI-COM485/4 is a four-port, asynchronous serial communications
card designed for use in PCI-Bus systems. The cards feature four
independent, asynchronous RS-485 serial ports, type 16550 buffered
UARTs, and for Windows compatibility, automatic control to transparently
enable/disable the transmission drivers. The card may be installed in any 3.3V or 5V PCI or PCI-X slot.
There
are two I/O Connector options. Model PCI-COM485/4 includes a single
25-pin connector on the mounting bracket plus a “spider” or breakout
cable that terminates in four 9-pin D-type male connectors. Thus, this
version only requires one I/O slot. The standard model PCI-COM485/4
S1 includes two 9-pin male connectors on the card mounting bracket
plus a second mounting bracket with two more 9-pin male connectors
plus ribbon cables to connect them to the headers on the card.
Each
independent port supports RS-485 balanced mode transmission/reception.
Each port has the 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 networks at each end of the networks should
be terminated to eliminate ringing. These cards support that need
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 multitasking systems while maintaining 100%
compatibility with the original IBM port.
A
crystal oscillator is located on the card and permits precise baud
rate capability up to 115,200. Higher baud rates, up to 460,800
baud, are achieved by changing a jumper on the card. The driver/receiver
used, type 75176, is capable of driving extremely long communications
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. PCI-COM485/4 supports
Half-Duplex communications with two-wire cable connections. Half-Duplex
allows traffic to travel in both directions, but only one way at
a time.
When
the card is first installed, Windows 95/98/NT 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 standard COM ports
at COM 5,6,7, and 8. You cannot set or change the card's base address,
you can only determine what the system has assigned. The PCI Bus
supports 64K of I/O address space so your card's address may be
located anywhere in the 0000 to FFFF range.
AUTO
RTS TRANSCEIVER CONTROL
In
RS-485 communications, the driver must be enabled and disabled as
needed, allowing all cards to share a two wire cable. The PCI-COM485/4
controls the driver automatically. With automatic control, the driver
is enabled when data is ready to be transmitted. The driver remains
enabled for one additional character's transmission time after data
transfer is complete and then is disabled. The receiver is also
normally enabled, then disabled during RS-485 transmissions, and
then re-enabled after transmission is completed (plus one character
transmission time). The PCI-COM485/4 automatically adjusts its timing
to the baud rate of the data.
Communications
Interface
- I/O Connection:
9-pin D-sub connectors.
- Serial
Ports: Four shielded male D-sub 9-pin IBM AT style connectors
compatible with RS-485 specifications. (Note: On model COM485/4,
the breakout cable terminates with four female D-sub 9-pin
connectors.)
- Character
length: 5, 6, 7, or 8 bits.
- Parity:
Even, odd or none.
- Stop
Interval: 1, 1.5, or 2 bits.
- Serial
Data Rates: Up to 115,200 baud, Asynchronous, A faster range
of rates, up to 460,800, is achieved by jumper selection on
the card. Type 16550 buffered UART.
- Address:
Continuously mappable within 000 to FFFF (hex) range of PCI
bus addresses.
- Receiver
Input Sensitivity: ±200 mV, differential input.
- Common
Mode Rejection: +12V to -7V
- Transmitter
Output Drive Capability: 60 mA, with thermal shutdown.
Environmental
- Operating
Temperature Range: 0 o to +60 o C
- Storage
temperature Range: -50 o to +120 o C
- Humidity:
5% to 90%, non-condensing.
- Power
Required: +5VDC at 125 mA typical, -12VDC at 5 mA typical,
+12VDC at 5 mA typical, 750 mW total power consumption.
- Size:
7.82" (198 mm) long by 3 7/8" (99 mm)
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