Measurement Computing CB-7011 - Manual (Page 63)

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CB-7011/CB-7011D, CB-7018 User’s Manual
ignore the digital output command @AADO(Data).
3.6 High/Low Alarm
Some analog input modules, such as the CB-7011, are
equipped with a 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 chang-
ing digital outputs 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:
Momentary alarm: the alarm status is cleared when the analog
input is not over the alarm value.
If Analog Input Value > High Alarm, DO1 (High alarm) is on,
otherwise DO1 is off.
If Analog Input Value < Low Alarm, DO0 (Low alarm) is on,
otherwise DO0 is off.
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