Fluke Biomedical 942A-200L-M4 - Manual (Page 57)

Operation
Set Point Descriptions
3
3-17
Overrange (Switch Position 4)
This parameter is entered in units of CPM. It is normally set for the upper limit value of the detector used
(for a 943-xx series detector, this value is normally 1.00E7). When the measured radiation value exceeds
this set point, the unit goes into a range alarm state. The overrange limit must be greater than or equal to
the HIGH or WARN setpoints.
Calibration Constant (Switch Position 5)
This parameter is a detector dependent value that is used to multiply the detector output by a fixed value
or to convert the counts per minute (CPM) output to engineering units, (i.e. µCi/cc). The actual value to be
entered is based on the detector and the sampling geometry used for the monitor. The units may be
µCi/cc per counts per minute, or other user defined value. The factory default value is 1.0.
Background Subtract (Switch Position 6)
This parameter is entered in units of counts per minute (CPM). The value entered is subtracted from the
radiation value calculated by the microprocessor, and the net result is displayed. The alarm limit checks
and analog output conversion are both processed based on the net count rate displayed, the background
subtracted value. The background subtract value does not affect the bargraph display, which is
processed based on the gross count rate.
Analog Low Scale Value (Switch Position 7)
This value is the dose rate at which the analog output is 0 volt or 4 milliamperes. This value must be an
even power of 10 that is at least 1 decade lower than the analog full-scale value. An even power of 10 is
a number of the form 1.00EX, where X equals -9 to +9. This parameter is entered in units of CPM and
sets the lower range of the analog outputs. This value must be set to exact decade values. Example:
1.00E-1 is acceptable, 2.00E-1 is not.
Calibrate Mode (Switch Position 8)
This function permits use of the UDR as a scaler, by entering a fixed counting time, and displaying the
integrated counts during this period. The units are entered in seconds.
Underrange Limit – Not Implemented
Unit ID (Switch Position F)
This setpoint is used in multidrop communication systems, where a unique address is required for each
UDR. The Unit ID has no impact on the operation of the 942A-200L-M4 or 942A-200L-M5.
3.13 Set Point Error Codes
If, after entering a setpoint or upon power-up, an error code is displayed, it may be due to incorrect
setpoints. If error code E0002 or E0008 is displayed, all alarms are inhibited. Refer to Table 3-4 for a
listing of error codes.
Code E0001 indicates that the display value is negative. Usually this means that the setpoint PROM is
bad or needs to be initialized. To initialize the setpoint memory to the default values, power up the UDR
with the ENTER button held down for approximately 5 seconds, or until the first digit on the display is
flashing. If initializing the setpoint memory does not help, then the setpoint PROM is defective or there is
a hardware malfunction.
Code E0004 indicates that a setpoint entry error has occurred (e.g. WARN alarm set higher than HIGH
alarm, HIGH alarm set lower than WARN alarm, OVERRANGE below HIGH alarm). The error code will
be displayed for approximately 5 seconds, and will automatically clear, returning to the set point entry
mode. The set point being edited should then be checked for agreement with the other related set points
prior to continuing the edit process.