SMAR LD291, Operation And Maintenance Instruction Manual

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Operation
2.5
Output
Calculates the current proportional to the process variable or manipulated variable to be transmitted on
the 4-20 mA output depending on the configuration in OP-MODE. This block also contains the constant
current function configured in OUTPUT. The output is physically limited to 3.6 to 21 mA.
Current Trim
The 4 mA TRIM and 20 mA TRIM adjustment is used to make the transmitter current comply with a
current standard, should a deviation arise.
User Unit
Converts 0 and 100% of the process variable to a desired engineering unit read out available for the
display and communication. It is used, e.g., to get a volume or from a level measurement, respectively.
A unit for the variable can also be selected.
Display
Can alternate between two indications as configured in DISPLAY.
The Display
The integral indicator is able to display one or two variables, which are user selectable. When two
variables are chosen, the display will alternate between the two with an interval of 3 seconds.
The liquid crystal display includes a field with 4 1/2 numeric digits, a field with 5 alphanumeric digits and
an information field, as shown on Figure 2.4.
DISPLAY V6.00
The display controller, from release V6.00 on, is integral to the main board. Please observe the new
spare parts codes.
Monitoring
During normal operation, the LD291 is in the monitoring mode. In this mode, indication alternates
between the primary and secondary variable as configured by the user. See Figure. 2.5. The display
indicates engineering units, values and parameters simultaneously with most status indicators.
The monitoring mode is interrupted when the user does complete local adjustment.
The display is also capable of displaying an error and other messages (See table 2.1).
INDICATES ACTIVE
CONSTANT OUTPUT MODE
INDICATES ACTIVE
TABLE FUNCTION
VARIABLE FIELD
%
F(x)
PV
Fix
UNIT PERCENT
UNIT AND FUNCTION FIELD
INDICATES THAT THE PROCESS
VARIABLE IS NOW DISPLAYED
INDICATES POSSIBILITY
TO ADJUST / CHANGE
VARIABLES / OPTIONS
MD
INDICATES ACTIVE
MULTIDROP MODE
Figure 2.4 - Display