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Appendix D: USB, RS232 & RS485
In addition to USB, The LCIC has an option for both full-duplex RS232
and half-duplex RS485 interfaces. These are brought out on CONN3, a 9
way ‘D’ type connector. The pin-out is as follows:
CONN3 PIN
FUNCTION
1
RS485-
2
RS232 TX (out)
3
RS232 RX (in)
4
NC
5
SIGNAL GROUND
6
RS485+
7
NC
8
NC
9
NC
i.e., for RS232 use pins 2,3 & 5 and for RS485 use pins 1,5 & 6
For RS232 connection, a standard direct (straight through) wired 9D M-F
cable can be used for direct connection to a standard 9 way ‘D’ type PC
COM port.
RS485 line termination – placing a jumper across the two rightmost pins
of LK1 puts a 120 Ohm (ac coupled) impedance across the RS485 data
lines. This should be used in single LCIC RS485 applications. In
applications where multiple LCIC boards reside on one RS485 bus, the
termination impedance should only be added on the last board on the bus.
D.1 Communication Parameters
For both the USB, the full-duplex RS232 and half-duplex RS485
interfaces, the communications parameters are fixed as follows:
Data 8 bits
Parity None
Stop Bits 1
_ This is generally referred to as “8,N,1”.