B&B Electronics Network Device I-7011 - Manual (Page 63)

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I-7011, I-7018 User Manual Rev:B1.0
3.6 High/Low Alarm
Some analog input modules, like I-7011, equip with the
high/low alarm function. When the alarm function is enabled, the
digital output DO0 is the low alarm indicator, DO1 is the high alarm
indicator, and the digital output command for changing digital out-
puts DO0, DO1 is ignored. The alarm function is to compare the
analog input value with given high alarm value and low alarm value.
And there are two alarm types as follows :
z Momentary alarm : the alarm status is cleared while the
analog input is not over the alarm value.
If Analog Input Value > High Alarm, DO1(High alarm) is on,
else DO1 is off.
If Analog Input Value < Low Alarm, DO0(Low alarm) is on,
else DO0 is off.
z Latch Alarm : the alarm is cleared only the user send com-
mand to clear.
If Analog Input Value > High Alarm, DO1(High alarm) is on,
else if Analog Input Value < Low Alarm, DO0(Low alarm) is
on.
3.7 Thermocouple Measurement
When two wires composed of dissimilar metal are joined at
one end and heated, the open circuit voltage is a function of the
junction temperature and the composition of the two metals. All
dissimilar metals exhibit this effect. The voltage is called “Seebeck
voltage”. For small changes in temperature the Seebeck voltage is
linearly proportional to temperature.