Lighthouse RLPC 0.1m, Operating Manual

Page: 39 / 118

Communications
248083227-1 Rev 8 4-7
RS485 Communications
Note:
Refer to “RS485
Adapter Cable” on page 3-
4 before setting up RS485
communications with the
RLPC.
The instrument can utilize RS485 communications if the distance to
the computer is more than 50 feet or the instrument will be used in a
multi-point daisy chain configuration.
To use the RS485 protocol with a computer COM port, an RS485
converter must be used in the 2-wire configuration with ChB+ wired to
the Cat5 cable pin 4, and ChA- wired to pin 5. Please contact a
Lighthouse Sales Representative for an RS485 converter kit that
includes the cables, connectors and terminators needed to set this up.
Connecting to a PC
To connect the instrument to a computer using RS485 Protocol:
1. Remove power from the instrument.
2. Connect one end of a standard Cat5 cable to an LWS RS485
converter.
3. Connect the other end of the Cat5 cable to the RS232/485 IN port
on the instrument.
4. Connect the RS232 DB-9 side of the RS485 converter to a DB-9
Male to DB-9 Female straight through cable. Connect the female
DB-9 to any available COM port on the computer.
5. Set DIP Switch 8 to OFF (DOWN).
6. Power on the instrument.
To daisy chain multiple units, use a Cat5 cable to connect the RS485
OUT port of the first instrument to an RS485 Adapter Cable (see
“RS485 Adapter Cable” on page 3-4) that is connected to the RS232/
485 IN port of the next instrument. Use adapters and ethernet cables to
connect the OUT ports to the IN ports of all the units and insert a 100-
ohm terminating block in the last instrument’s OUT port. See Figure 4-
3.
Figure 4-3 RS485 Adapter Cable