Serial slave communications – Red Lion LDSS User Manual
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This parameter allows the Main and/or Secondary display (if enabled) to
automatically reset when power is applied to the unit.
DISPLAY RESET AT POWER-UP
The Security Code determines the user access to Programming mode. This
code can be used independently or along with the Program Mode Lock-out
(
) selection in the User Input Function parameter (Module 1).
Programming a Security Code other than 0, requires this code to be entered
at the
prompt in order to access Programming mode.
PROGRAMMING SECURITY CODE
The
selection returns the slave to the factory default settings. The unit will
displays
and returns to
, with the factory settings loaded.
LOAD FACTORY DEFAULT SETTINGS
to
Enter the desired display intensity level. The display will actively brighten or
dim as the level is changed.
DISPLAY INTENSITY LEVEL
USER INPUT
FUNCTION
USER INPUT
STATE
SECURITY
CODE
PROGRAMMING ACCESS
WHEN “PAR” PRESSED
0
Immediate Access
not
______
1-999
0
Programming Locked
No Access
Active
1-999
With correct code entry
at
prompt *
Not Active
0-999
Immediate Access
With correct code entry
at
prompt *
* Entering Code 222 allows access regardless of security code.
to
Select
to insert blanks in place of any leading zeros received in a serial
data string. This is typical when sending numeric values to the slave. Select
to enable display of any leading zeros in the string. This parameter setting only
applies to the Main display.
LEADING ZERO DISPLAY ENABLE
Serial Slave Communications
Displayable Characters
The ASCII characters that the Serial Slave can display are as follows:
Numeric: 0 to 9
Alphabetic (7-segment): A, b, C, c, d, E, e, F, G, g, H, h, I , i, J, K, L, l, N,
n, O, o, P, q, r, S, t, U, u, V, v, Y, Z
Non-displayable alphabetic characters will be replaced with a blank if
received. These include M, W and X.
Note: Both uppercase and lowercase ASCII characters are accepted. If a
displayable difference exists, characters will be shown in the case received.
Punctuation: period, comma, and colon (all displayed as decimal point);
minus (dash), blank
Display and Serial Buffer Capacity
The Serial Slave display is right aligned and has the capacity of displaying six
characters. When less than six characters are received, blank spaces are placed
in front of the characters. If more than six characters are received, only the last
six are displayed.
The unit has two internal display buffers, allowing two separate values or
messages to be viewed. The main display is always enabled and viewable. The
secondary display may be enabled or disabled through programming. When
enabled, this display is indicated by a “2” on the far right of the display. The
main and secondary displays can be toggled either manually or automatically at
a user selectable toggle speed. A serial command can also be sent to select which
display is shown. Both displays are retained in memory when power is removed
from the unit.
The Serial Slave has an internal 64 character buffer for received data. If more
than 64 characters are sent, the additional characters are discarded until a string
terminator
the buffer are displayed.
A carriage return
However, if an <*> or <$> is received, the slave will empty and reset its internal
character buffer without processing the string. These characters are used as valid
command terminators for serial commands sent to other Red Lion meters. Since
these commands are not applicable to the Serial Slave, the slave discards the
command and prepares its character buffer for a new data string.
Data and Command String Formatting
Data sent to the Serial Slave must be formatted as either main display data,
secondary display data or command strings sent to perform specific display
functions. The format for sending data is shown below:
N xx I d6 d5 d4 d3 d2 d1
N - Required to address a specific slave unit in a multiple unit loop.
xx - Two-digit meter address. Single digit address requires leading zero.
I - Format identifier character (see below). Omit for main display data.
d6-d1 - The last 6 characters before the
The format identifier character dictates how the Serial Slave interprets a
data string as follows:
(omit) - No character indicates main display data
# - Indicates secondary display data
@ - Display select command, followed by display identifier character
main <1> or secondary <2> (ex: @1
% - Display intensity command, followed by intensity level character
<1> to <5> (ex: %3
Downloading Data from a G3 to an LDSS
Communications:
Port: RS232 Comms Raw Serial Port
Port Driver:
Programming:
PortPrint(2, "N01" + IntToText(Var1, 10, 6) + "\r");
This program is called from the Global On Tick. It sends “N01” (the address
of the LDSS), followed by the ASCII equivalent of Var1, then a carriage return.