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CHAPTER 3: CONFIGURING THE D20E FIRMWARE
Analog input points
Analog value type
Analog report deadband
Analog alarm threshold, hysteresis and qualification period
D20E ETHERNET I/O MODULE INSTRUCTION MANUAL
The D20E-A module allows up to 32 analog inputs and the D20E-C allows up to 16 analog
inputs.
The D20E-A analog input can be set from 1 to 20 mA current or from 5 V differential
voltage input. All input can be scaled with a full range of Short or Long Floating; and Signed
or Unsigned Integer (16-bit or 32-bit).
When an input value exceeds the maximum range, the analog input appears with the
maximum value and an Over Range flag is set on the point quality.
Specify the size of change between the new value of an analog input and the previous
value before the application reports the new value to the system point database. Use this
option to control the number of data change-of-events generated for an analog input. The
default value is zero; that is, the deadband function is disabled, and the device reports all
changes.
Each Analog Input point can generate an alarm while the input is under an abnormal
condition. The alarms are configurable for each input separately. In order for an alarm to
function properly, the parameters shown in Table 12 are configured.
Table 12: Alarm function parameters
Alarm parameter
Description
Threshold:
The threshold specifies a value of an analog input when an alarm is to be
triggered. When the analog input is above or below this threshold, the analog
alarm enters its qualification period. After the qualification period has expired,
the alarm is triggered.
Hysteresis:
The hysteresis is the value that an analog input must return to, in order for the
alarm to be deactivated, or the qualification period to be reset. Normally in:
• High alarm the hysteresis value is lower than the threshold, and
• Low alarm the hysteresis value is higher than the threshold.
Qualification Period: The qualification period is the length of time that the monitored analog input
value must be within range, so that the alarm can be activated.
During this period, if the analog input returns to within the normal range, the
alarm is not triggered (see the example in the right hand side of Figure 11). The
purpose of implementing a qualification period is to disallow a short pulse high
input from triggering a false alarm. The qualification time could be set on
milliseconds or a number of power cycles.
GE INFORMATION
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