Teknor Industrial Computers VIPer 821 Technical Reference Manual page 35

Serial Port 2 is available through the J9 connector and supports both RS-422/RS-485 and
RS-232 operation modes.
SETUPS
Related Jumpers
If required, for RS-485 mode operation, termination resistors can be tied to the RX and TX
pairs of the Serial Port 2 by shorting respectively the W6 and W7 jumpers.
BIOS Level
The following settings are available through the BIOS Setup program:
IRQ monitoring
Port Address/IRQ assignation
Port Mode
MAKING CONNECTIONS
The usual way to connect a device to a serial port is to issue signals through a 10-pin
header/D-Sub 9-pin adapter cable. An 18" 10-pin header/D-Sub 9-pin adapter cable is
available from TEKNOR and is referred to as #150-019.
MORE ...
In RS-485 mode the Serial Port 2 supports either full-duplex or party line operation:
Full-Duplex – upon power-up or reset, the COM2 interface circuits are automatically set for
full-duplex operation". Pin 3 and 4 of J9 act as the receiver lines and pin 5 and 6 act as the
transmitter line.
Party Line – to enable party line operation, set the bit 2 of I/O port 190h (or 290h or 390h,
depending on the I/O base address value – see BIOS Setup program, Chipset Feature
option). The transceiver lines (pins 3 and 4 of J9) will be controlled by the RTS signal. Upon
power-up or reset, the transceiver is by default in "receiver mode" to prevent online
perturbations. If the board is placed at one end of the network, use W6 and W7 jumpers to
enable termination resistors.
  '   !+      %  %  %  %   '   !+    '   !+    '   !+ 
see Power Management Setup option
see Integrated Peripherals option
see Integrated Peripherals option
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