CONFIGURING THE SERIAL PORTS
SNAP-LCSX AND LCSX-PLUS Installation Guide
17
Pin Connections for COM2
CONFIGURING COM PORT 3 (SNAP-LCSX-PLUS ONLY)
The default for COM3 is RS-232, but this port can also be configured as RS-485 two-wire or four-wire. Jumpers
1C–1G control the mode for COM3. The grayed-out jumpers are shown for reference only.
NOTE: The mode may be shown incorrectly on the board itself. Use the diagrams below to set the mode.
COM3 RS-232 Configuration
COM3 RS-485 Configuration
Pin
RS-232
RS-485 2-wire
RS-485 4-wire
1
TX
TX/RX +
TX +
2
RX
TX/RX -
TX -
3
COM
COM
COM
4
RTS
IRQ +*
RX +
5
CTS
IRQ -*
RX -
TX = Transmit
RX = Receive
COM = Common
Ground
RTS = Request to
Send
CTS = Clear to Send
IRQ = Interrupt
*NOTE: For 2-wire, use pins 4 and 5 only
if you are using an interrupt (IRQ). The
IRQ function is supported in 2-wire mode
only. Use pins 4 and 5 for the IRQ wires
and leave jumper H out.
Pin 1
RS-232 Mode (default)
JP1
JP7
A B C D E F G
1
RS-485 Mode
JP1
JP7
A B C D E F G
1
