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Appendix
Transmitter control
With transmitter control, the Vapor-logic4 board receives a signal
that corresponds to the actual humidity level measured in the space
being controlled. (With a transmitter provided by DRI-STEEM,
the signal is 4 to 20 mA, which corresponds to 0 to 100% RH). The
Vapor-logic4 controller employs an internal PID loop that uses
this humidity measurement along with a user-defined humidity
set point to calculate a demand level. This demand level is the level
at which the humidifier will run. For more information about the
PID control loop, see Page 47.
A p p e n d i x :
C o n t r o l i n p u t s i g n a l s
Calculation of transmitter % RH
% RH = (mA reading) – 4
0.16
Example: 12 mA – 4 = 50% RH
0.16
