Connect Tech Xtreme/104-Plus, PCI-104 and PCI/104 Express Family User Manual
Revision 0.09
22
15.3.3
Jumper Details
RS-485 Selection
: Install this jumper to configure a port for RS-422/485 mode. If the jumper is
not installed, the port will function in RS-232 mode.
TxD Control
: Install this jumper to only enable the RS-485 transmitter when sending data. This
mode is useful for half-duplex operation when only one device is allowed to send data at a time.
If the jumper is not installed, the transmitter will always drive the line to an idle state when not
sending data.
RxD Control
: Install this jumper to enable the RS-485 receiver only when NOT transmitting
data. This is useful for half-duplex operation to prevent the transmitting device from receiving
its own data as it sends. If this jumper is not installed, the receiver is always enabled and ready
to receive data.
RxD ± Termination/Bias
: Install this pair of jumpers to enable a 150 ohm terminator across the
RxD+ and RxD- pins for the corresponding port. A biasing network is also enabled that drives
the receiver to an inactive or safe mode. The receiver can still receive data from another device
and the biasing helps to prevent the reception of data generated by noise on the transmission
line. The two jumpers for RxD termination/bias must be installed and removed as a pair.
TxD ± Termination
: Install this jumper to enable a 150 ohm resistor across the TxD+ and TxD-
pins of the corresponding port.
Important Port Numbering Note for some Xtreme/104
Plus
models
:
Due to differences between the quad and octal UARTS, the port numbering
for eight port models differs from the numbering for four port models.
Jumper blocks JA through JD control ports 1 through 4, respectively, on four
port models.
On eight port models, jumper blocks JA through JD control the odd numbered
ports and JE through JH control the even numbered ports, as follows:
JA = Port 1, JB = Port 3, JC = Port 5, JD = Port 7
JE = Port 2, JF = Port 4, JG = Port 6, JH = Port 8.
Note: this does not apply to Xtreme/104 Express and Xtreme/104 Plus 16 port
models
Half Duplex
and
4-wire Multi-drop
modes require you to select the appropriate
mode via software. Please refer to the
readme.txt
files found in the appropriate
directories on the Xtreme/104-
Plus/Express
CD.
