High Country Tek emc-3L - Manual (Page 24)

connected to the digital input) for the switch as well as the digital input pin where the switch being open or
closed is received. The DVC710 has a single +5vdc regulated Reference output capable of driving up to 500ma
of current. To use a Digital Input in sourcing mode on a DVC710, an external series resistor must be used to
limit the current sourced from the internal reference voltage regulator to prevent shorting the reference voltage
to ground through the inputs switch. A 1K ohm 1 Watt resistor will protect the reference voltage regulator from
both shorts to ground and supply power.
The two configurations of digital inputs supported by the DVC hardware are:
Note: the DVC circuitry senses the voltage change at the edge of the waveform and if the transition state is the
same after the de-bounce time interval then the new state is deemed valid and communicated to your
application via the input’s variable name.
To configure a digital input, click one of the Digital Input buttons on the DVC
screen. The Name field’s value is the way this input will be referenced in your user
application. It is a good idea to name the input to reflect its function.
The De-Bounce Time setting is used to avoid recording momentary spikes on the
input as valid state changes. The polarity determines what voltage level is
interpreted as a true or false or which edge causes a change in the state of the
input.
In No Toggle mode, the state of the input flag will change to True any time the
Active Polarity Input condition is met after the De-Bounce time and back to False if
it is not met.
In Toggle mode, the input state is set to True on the first occurrence of the Active Polarity instance and
remains true until the second instance of the Active Polarity, always observing De-Bounce time. For an input in
Toggle mode the application program can also set the input state at any time.
Digital Input 1 can be configured to be in System Disable mode. When this System Disable mode is selected
and the digital input is in a true state, the BIOS will automatically turn off all of the current paths to the valves
and require a power cycle to resume operation.
Sourcing (DVC's 5V Ref Powered Switch) Sininking (Externally Powered Switch)
DVC +5 Volt Ref
Note: Regardless of what type of digital input switch configuration is used, the DVC will respond according to the
voltage seen at the input. See the hardware manual for instructions on hooking up a switch in order to provide
the desired voltage levels.
The following subsections give the definition as well as an overview of each of the fields in the Digital Input
screen:
1 K
1
2
PWR GND
SW
1 2
DVC Digital Input DVC Digital Input
SW
1 2
+PWR
Digital Input Setup
Screen
P/N: 021-00163, Rev. A.0 - for V5.2 Tools Page | 24