Technical Description
Sealevel Systems
PCIO
Page
8
Technical Description
The
PCIO
adapter utilizes the 16550 UART chip. This chip features
programmable baud rate, data format, interrupt control and has a 16 byte
transmit and receive FIFO. The
PCIO
also provides one Centronics
compatible parallel port for printers and bi-directional (IBM Extended
Mode) capability for general purpose parallel I/O. The
PCIO
supports
edge-triggered interrupts and a readable interrupt-pending status.
Features
•
IBM/Centronics compatible parallel printer port
•
IBM Extended Mode (bi-directional) compatible
•
User selectable (via DIP-switch) addresses of LPT1 -3:, any other
I/O address or disabled
•
Serial port configurable for RS-232/422/485
•
Addressable as COM1: - COM4: or any other I/O address up to
3FF Hex
•
‘Shareable’ IRQs allow more than one port to share a single IRQ
•
IRQ's 2/9, 3, 4, 5 supported
•
Support for non-standard baud rates available. These baud rates
(such as 31.25K or 76.8K baud) are supported by installing a
different oscillator. Please consult Sealevel Systems Technical
Support for more information
Modem Control Signal Considerations
Some software packages require the use of the modem handshake signals
such as CTS or DCD. Refer to your application software manual to
determine the requirements for modem control signals. If no
requirements are mentioned, a safe configuration is to tie DTR to DSR
and DCD, and tie RTS to CTS. This configuration will typically satisfy the
modem control signal requirements for most communications software.
Line Termination
Typically, each end of the RS-422/485 bus must have line terminating
resistors. A 100 ohm resistor is across each RS-422/485 input and a 1K
ohm pull-up/pull-down combination bias the receiver inputs. If more than
two RS-485 nodes are configured in a multi-drop network, only the nodes
at each end of the bus should have the 100 ohm resistors installed.
Содержание PCIO 4035
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