Watlow D4T Data Logger
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Chapter 5 Function Reference
Sample and Hold
When the Hold input is off, the output follows the IN value. When Hold is on, the output stops
changing; the output stays at the value it had at the time Hold turned on.
A filter and offset may be applied to the output value. Filtering holds when the Hold input is
on. Changes to the offset are applied without filtering and are not affected by the Hold input.
The output has the same units as the input (IN).
Signals
Direction
Label
Type
Function
Receivers
IN Analog Input to math function
Hold Digital
When off the output follows the input plus the offset. When
on the output stops following the input and holds the input
value present at the time hold turned on.
Transmitter - - - - Analog Filtered value of input (IN) plus the offset when HOLD is off.
Holds the output once HOLD turns on.
Function
To freeze the analog signal with a digital input, set Function to
Sample and Hold
.
Offset
Adjustment added to the result of the calculation.
Range: -99,999.000 to 99,999.000
Filter
Set the amount of filtering to apply. Filtering smooths signal fluctuations. Increase the time to
increase filtering. Excessive filtering slows the function’s response.
Range: 0.0 to 60.0 seconds
Pressure to Altitude
This function determines the altitude based on the atmospheric pressure. A filter and offset
may be applied to the calculated value. The output has the units selected with the Altitude
Units parameter.
The calculation is based on the International Standard Atmosphere 1976 and is accurate from
sea level to 90,000 feet. It can be used beyond this range in both directions, but with loss
of accuracy. The standard is based on an altitude of 0 feet (sea level) pressure of 14.6967 PSI
and a temperature of 59 °F.
Signals
Direction
Label
Type
Function
Receiver
- - - - Analog
Pressure (See Pressure Units parameter)
Transmitter - - - - Analog
The calculated altitude plus the offset (See Altitude Units
parameter).
Function
To calculate the standard distance above sea level based on an atmospheric pressure, set
Function to
Pressure to Altitude
.
