Red Lion LDSS - Manual (Page 4)

4
3.0 R
EVIEWING THE
F
RONT
P
ANEL
K
EYS AND
D
ISPLAY
2
DISPLAY DESIGNATOR
“ 2 ” - To the far right of the display indicates the secondary display is shown.
If display scroll is enabled, the display will toggle automatically between the main and secondary display at the selected scroll interval.
RS485 Communications
The RS485 communication standard allows the connection of up to 32
devices on a single pair of wires, distances up to 4,000 ft. and data rates as high
as 10M baud (the LDSS is limited to 38.4k baud). The same pair of wires is used
to both transmit and receive data. RS485 is therefore always half-duplex, that is,
data cannot be received and transmitted simultaneously.
RS232 Communications
RS232 is intended to allow two devices to communicate over distances up to
50 feet. Data Terminal Equipment (DTE) transmits data on the Transmitted Data
(TXD) line and receives data on the Received Data (RXD) line. Data Computer
Equipment (DCE) receives data on the TXD line and transmits data on the RXD
line. The LD emulates a DTE. If the other device connected to the meter also
emulates a DTE, the TXD and RXD lines must be interchanged for
communications to take place. This is known as a null modem connection.
2.3 SERIAL WIRING
TBD
A
COMM
RXD
TXD
4
2
3
1
B 5
232
485
5
4
3
RS485 Terminal Block Connection Figure
1
2
3
RS232 Terminal Block Connection Figure
The serial connections are made via terminal block TBD located inside the
unit on the left side for the LD2 and on the right side for the LD4.
KEY DISPLAY MODE OPERATION PROGRAMMING MODE OPERATION
PAR Access Programming Mode Store selected parameter and index to next parameter
SEL  Select display (main or secondary) Advance through selection list/select digit position in
parameter value
RST  Reset display(s) per front panel reset setting Increment selected digit of parameter value