Themis NanoPAK, Руководство пользователя

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NanoPAK
®
User Manual Version 1.0
2-10
Themis Computer
The selection between RS232, RS422, and RS485 modes is done through a combi-
nation of solder bead settings, as indicated in
Table 2-4 .
When the differential mode is chosen, it is necessary to “insert” a parallel termina-
tion, as indicated in
Table 2-5 .
See Table A-5, "Solder Bead Settings," on page A-11 of Appendix A for further
details.
RS485 mode is designed for multipoint communication and can run either in half-
duplex or full-duplex mode. When the half-duplex mode is selected, the transmitter
enable signal is controlled by the TXD TTL signal from the serial controller. The
following figures illustrate the typical network topology for RS422 and RS485 com-
Table 2-4. COM A Solder Bead Settings Matrix
Mode
Solder Beads Setting
SB2 SB3 SB7 SB8 SB9
RS232 2-3 2-3 ON OFF OFF
RS422 2-3 2-3 OFF ON OFF
RS485
HALF-DUPLEX ENDPOINT 1-2 1-2 OFF OFF ON
FULL-DUPLEX ENDPOINT 2-3 2-3 OFF ON ON
HALF-DUPLEX MIDPOINT 1-2 1-2 OFF OFF OFF
FULL-DUPLEX MIDPOINT 2-3 2-3 OFF OFF OFF
Table 2-5. Mode Terminations
Mode Termination
RS232 NONE
RS422 One (RX)
RS485
HALF-DUPLEX ENDPOINT One (Common RX and TX)
FULL-DUPLEX ENDPOINT Two (RX and TX)
MIDPOINT NONE