2 — INSTALLATION SPECIFICATIONS AND WIRING
pg. 19
Curtis Model 1351 – December 2018
Switch (digital) Inputs
The controller offers flexibility in configuring the analog/digital inputs as Off/On switch signals. All
switch inputs have a pull-down resistor. Some have an additional selectable pull-up resistor, and a
few can be enabled to become floating input (no pull-up with high impedance pull-down resistor).
When the Pull-down is enabled, wire the switch input to connect to B
+
when “switched” On. With
the pull-up enabled, the switch can be connected to B
−
(ground) when “switched” On. When left
floating, the input can be driven by a TTL or voltage device (i.e., not the typical toggle switch). The
control of the pull-up/pull-down resistors state (Pull-Up, Pull-Down or Float) is by the Open State
parameter for each switch when the input is being used as a switch.
In all cases, the input level that is considered ON is set by the Active State parameter.
If
Active Level = Low
, and input voltage is less than 1V, the State will be
On
Alternatively,
If
Active Level = High
, and input voltage is greater than 4V, the State will be
On
Virtual Switches
Analog inputs 1 through 11 are also monitored as virtual digital inputs by comparing high and low
threshold parameters and then applying the Active Level parameter. These are called
Virtual Switch
Inputs
. They are configured using parameters VSW1-11 (virtual switch 1 thru 11). The result is placed
in the VCL variables
Virtual_Switch_X
(where X is 1 through 11). See
for the comparison
between Switches and Virtual Switches.
