Technical Description
Sealevel Systems
485I
Page
9
Technical Description
The
485I:
utilizes a USB UART. This chip features programmable
baud rate, data format, 128 byte Dual Port TX Buffer, and 384 byte Dual Port
RX Buffer. The RS-422/485 transceiver supports data rates up to 921.6K baud.
Features
•
Hot-Pluggable device
•
Does not require opening the case
•
No system resources are required (i.e. I/O ports or IRQ’s)
•
LED status indicators for “USB Enabled”, “TD”, and “RD”
Connector Pin Assignments (DB25 Male)
The
485I
complies with the EIA-530 pin out with the following
signals supported
Signal
Name
Pin
#
Mode
GND
Ground
7
RDB
RX+
Receive Positive
16
Input
RDA
RX-
Receive Negative
3
Input
TDB
TX+
Transmit Positive
14
Output
TDA
TX-
Transmit Negative
2
Output
Technical Note: The modem control signals are biased as follows : RTS is
connected to CTS, DTR is connected to DCD and DSR, and RI is tied
inactive
.
