System information

76
Voltage Command Box
The Voltage Command Box is an external control device, which
provides twenty logic input/output connections. When a Voltage
Command Box is placed, an Initialization Properties dialog box
appears for assigning the quantities of logic inputs/outputs (20
total). Logic inputs allow external switches to initiate E Desk
actions. Actions can be individual or grouped functions within E
Desk. This includes recalling presets, ducking, combining, etc.
Logic outputs can be used to control additional equipment,
external to E Desk.
Voltage Command Box components have no Control Dialog Boxes. They are represented in the layout as a block
with a total of twenty control input/output nodes. Logic Inputs (on the box) are represented as control output nodes
(on the block). These control output nodes may be connected to control input nodes on other components, such as
Remote Preset Buttons, Duckers, and Room Combiners. Logic Outputs (on the box) are represented as control input
nodes (on the block). These control input nodes may be connected to control output nodes on other components, such
as Auto Mixers, Duckers, and S8. Unlike other components, Voltage Command Box output nodes may be connected
to input nodes on the same Voltage Command Box block, allowing Logic Inputs (external switches) to control Logic
Outputs (external equipment).
Voltage Command Box behavior can be altered using Logic Gates. Please refer to
the 'Installation Guide
' (included with controls), or see Control Bus for more
information. External controls must be identified (see Device Maintenance) and
associated with their corresponding component blocks within the layout (see
Equipment Table).
Up to 20 logic inputs are availble on the Voltage Command Box. Logic inputs allow remote control of E Desk via
external circuits such as switches, relays, and logic outputs from other devices. When nothing is connected to a logic
input, an internal pull-up resistor keeps it at a ‘high’ state (+5.0 VDC). The logic input is activated when its input goes
‘low’ (less than +0.8 VDC), and is de-activated when its input goes ‘high’ (greater than +2.0 VDC). A logic input can
be controlled in one of three ways: 1) Using an ‘open-collector’ or ‘open-drain’ logic output from an external device
to short the logic input to ground. 2) Using a switch, relay, or other contact-closure to short the logic input to ground.
3) Using an active 5V TTL output driver circuit (such as from a third-party controller) to actively drive the logic input
to a ‘high’ or ‘low’ state. Multiple contact-closures or ‘open-collector’/’open-drain’ logic outputs may be wired in
parallel to a single logic input (see diagram below). Open-collector or open-drain logic outputs and contact-closures
should be rated for at least 5 Volts / 1mA operation. Active output driver circuits should not exceed a signal range of
0~5 Volts DC, and should have a minimum pulse width of 10 milli-seconds. The logic input impedance is
approximately 10k ohms.
The Voltage Command Box provides up to 20 logic outputs. Logic outputs can be used to control relays and indicators
or to drive logic inputs of other devices. The Voltage Command Box logic outputs are ‘open collector’ with an internal
pull-up. Each logic output is an NPN transistor with the collector being the output and the emitter being ground (see
diagram below). When a logic output is turned on, the transistor provides a path for DC current to flow, lowering the
output voltage to below 0.8V. When a logic output is turned off, the internal pull-up resistor raises the output voltage
to near 5V, depending on the output current. To activate external relays or indicators, an external power supply must
be used (see diagram below). The logic output transistors are rated up to a maximum of 40 VDC and 500 mA per
output (24 volt relay coils maximum). However, +12 Volts DC is sufficient power for most applications. When using
the logic outputs to control relays, protection diodes must be used to suppress high voltage transients that are generated
when the relays turn off (see diagram below).