Ampro Corporation P5X 用户手册
2–18
variety of embedded applications requiring low-to-medium-speed data transfer between two or more
systems.
systems.
Note
When you configure Serial 1 for RS-485, you cannot use the port for
RS-232.
RS-232.
Serial 1’s RS-485 interface appears on J20, a two-pin connector. The pinout for J20 is shown in
Table 2– 13. Table 2– 14 shows a compatible mating connector to J20.
Table 2– 13. Table 2– 14 shows a compatible mating connector to J20.
Table 2– 13. Serial 1 RS-485 Connector (J20)
J20 Pin
Signal
1
-I/O
2
+I/O
Table 2– 14. J20 Mating Connector
Connector Type
Mating Connector
Discrete Wire
(Locking Connector)
MOLEX Housing 22-01-2027
Pin 08-55-0102
The RS-485 interface specification requires that both ends of the twisted-pair cable be terminated
with 100 ohm resistors. You can terminate the RS-485 interface on J20 with a resistor provided on
the LittleBoard/P5x. To terminate the line, install a jumper on W1, as shown in Table 2– 15.
with 100 ohm resistors. You can terminate the RS-485 interface on J20 with a resistor provided on
the LittleBoard/P5x. To terminate the line, install a jumper on W1, as shown in Table 2– 15.
Table 2– 15. RS-485 Termination
W1
Result
On
Connects a 100 ohm termination resistor
between J20-1 and J20-2.
between J20-1 and J20-2.
Off
No termination
Serial TTL Option
Serial 2 and Serial 4 can be configured for TTL operation. Of the serial ports’ output signals, just
the transmit (TxD) is supported for TTL. All of the serial ports’ input signals are supported by
virtue of the fact that the inputs of the RS-232C buffers used on the Little Board/P5x can function
as TTL inputs.
the transmit (TxD) is supported for TTL. All of the serial ports’ input signals are supported by
virtue of the fact that the inputs of the RS-232C buffers used on the Little Board/P5x can function
as TTL inputs.
The TxD signal for Serial 2 appears on J11-20. The TxD signal for Serial 4 appears on J13-20. The
other serial port signals appear in J11 and J13 as shown in Table 2– 11.
other serial port signals appear in J11 and J13 as shown in Table 2– 11.