Bio-Rad Model 550, Ultramark, and Benchmark Microplate Reader Accessories - Manual (Page 15)

4. Under three different sets of conditions, an error may be made in cal-
culation of the calibration curve and an error message will be printed on
the Concentration report, ERROR: Calibration Curve. Despite the error
message, the software does make a calibration curve and uses it to report
concentrations. In all three cases, it probably indicates an error was
made in preparation of one or more of the standards.
a. If the absorbance of any standard is measured as a negative value.
b. If the sign of the slopes of the different line segments changes. For
example, if the standard concentrations are input in decreasing order,
then normally the slopes of the individual lines joining consecutive
data points would be negative. If any one segment is has a positive
slope, the error is message is displayed.
c. If the slope of any one line segment is zero, i.e., the same absorbance
is measured at two different concentrations.
5. If any sample absorbance is out of range, asterisks will be printed on
the Concentration report. The asterisks will be preceded by a negative
sign (-) if the sample absorbance is below -3.500.
For example: Samples = 20, Repl = 2
# Conc. Abs.
1 ***.* *.***
2 0.020 2.550
6. If a sample absorbance is less than zero (i.e. a negative number), the
sample concentration will be displayed with asterisks, but the actual
absorbance is printed.
For example: Samples = 20, Repl = 2
# Conc. Abs.
1 -***.* -0.123
2 -***.* -0.234
7. If the calculated concentration is above 999.9 or below 0.000, the
reported concentrations will be ‘***.*’ or ‘-***.*’, respectively.
For example: Samples = 20, Repl = 2
# Conc. Abs.
1 ***.* 2.567
2 -***.* 0.010
RS-232 Interface
This microplate reader has a built-in bidirectional RS-232 interface. This allows external
computers to control the instrument. When an external computer is in control of the microplate
reader, the printer is automatically deactivated and the display will indicate
The reader will remain in remote control mode until it receives an ‘RL’ command from
the host computer or until the Start/Stop button on the microplate reader is pressed.
12
Remote
Control Mode