Kontron PCI-COM422, Руководство пользователя

Страница: 21 / 36

PCI-COM422 User’s Guide page 21
Option Selection
To help you locate the jumpers described in this section, refer to the Option Selection
Map at the end of this section. Operation of the serial communications section is
determined by jumper installation as described in the following paragraphs.
Terminations
A transmission line should be terminated at the receiving end in its characteristic
impedance. Installing a jumper at the locations labeled LDxO and LDxI apply a 120
Ω
load across the transmit/receive input/output for RS422 operation.
Figure 1: Simplified Termination Schematic
In RS422 operations where there are multiple terminals, only the RS422 ports at the
receiver end of the network should have terminating impedance as described above. To
terminate the COM A port, place a jumper at the location labeled LDAO. To terminate
the COM B, COM C, COM D, COM E, COM F and COM H ports, place jumpers at
locations labeled LDBO, LDCO, LDDO, LDEO, LDFO LDGO and LDHO respectively.
Similarly, Inputs are terminated at jumpers labeled LDAI, LDB1, etc.
Also, for RS422 operation, there must be a bias on the RX+ and RX- lines. If the card is
not to provide that bias, contact the factory technical support.
Data Cable Wiring
SignalPin Connection
Ain-
1
Aout+ 2
Aout- 3
100 Ω to Ground 5
120
0.1 F
Tx+/Rx+
Tx-/Rx-
COM422LD
µ