Watlow D4T Data Logger
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Chapter 5 Function Reference
Off Delay
Set an amount of time the output signal remains on after the Minimum On Time is satisfied
and the signals at A and B indicate the compressor is no longer needed. This prevents the
compressor from turning off prematurely due to a transient condition such as opening a door.
Range: 0 to 9,999 seconds
Note:
During the Off Delay, if either channel's power signal drops below its turn off setting, the
compressor stays on and the Off Delay timer is reset. The timer starts again when A and B
are each above their Turn Off levels.
Time Delay
Set how long the compressor remains on while 0% power is received from the control loops.
This feature turns the compressor off when the power from the control loops is 0% for longer
than the Time Delay setting. Use the Time Delay to distinguish between the case where the
power is 0% because the loop is turned off, and the case where the power is 0% for a short
time when a loop switches from heating to cooling. To ensure the compressor stays on when
needed, but turns off when the control loops are off, set the Time Delay longer than the time
the loop outputs are at 0% in normal operation. If two loops are connected to the Special
Output function block, the Time Delay feature looks for both loops to output 0%. When the
Time Delay is set to 0, this feature is disabled.
Range: 0 to 9,999 seconds
Thermistor Input
Use this block to condition a temperature measurement made with a thermistor. This FB is
found on the canvas of the FB diagram. The number of these FBs that are available depends
on the number of installed flex modules with thermistor inputs.
The module number shown on the block is the number of the data logger’s slot that houses
the flex module with the thermistor input. The Thermistor Input number indicates the specific
input on the flex module.
Signals
Direction
Label
Type
Function
Transmitter - - - -
Analog
The measured temperature with filter and offset applied
This function includes three curves pre-programmed for use with popular sensors selectable
with the Thermistor Curve parameter. See the table. It also can be user-configured for other
sensors by entering the Steinhart-Hart coefficients for the thermistor.