Ross Opengear UDC-8625A Series, User Manual, Page: 47 / 174

UDC-8625A Series User Manual (Iss. 11) Configuration • 3–7
Setting up GPI/Tally Communications
This section explains how to configure communications for GPIs and Tallies on the card using the
menus and options available in DashBoard. Each of the GPI/O ports can be configured as a GPI
or Tally output.
GPI Overview
When configured as a GPI, a port behaves as an input, and can be used to trigger actions such as
Cut/Dissolve the Key and/or Background. A push-button switch, or an ON-OFF switch, may be
directly connected between the port and the adjacent ground pin. Alternatively, an external device
may drive a low level. Minimum pulse duration is 1ms, anything shorter will be filtered out.
Typically, users will configure the GPI for Edge trigger. This means that the action is carried out
either on the falling edge (button is pushed), or rising edge (button is released), depending on
which Polarity is selected. Alternatively, users may configure the GPI for Level trigger. In this
mode, the action is carried out on both the rising and falling edges, so there are effectively two
states. The Polarity control can be used to invert the behavior. Regardless of the trigger type, GPI
commands may be overridden by other command inputs such as serial protocols.
Edge
This option enables the GPI to act as a latching trigger. Edge triggers are used when you want to
toggle between settings. This option enables the GPI to execute a specific function.
• If configured for Falling Edge, the selected function is executed when the GPI input
signal transitions from High to Low.
• If configured for Rising Edge, the selected function is executed when the GPI input
signal transitions from Low to High.
• Edge triggered GPI signals are sampled once a frame and the associated function is
executed only once per frame. The minimum pulse width is 1 millisecond.
• Typically, the edge triggered GPI is driven by external equipment that generates one
pulse per event.
Level
Level triggers are used when you want to assert a particular state for a setting. You define the
on-air state of the function as being either Level High or Level Low. Therefore, if the on-air state
of the Key is defined as Level High for example, when the GPI is a Level High signal, the Key
will stay on air. If a Level Low is received, the Key will be taken off air.
• If configured for Active Low, the selected function is executed when the GPI input signal
is driven Low.
• If configured for Active High, the selected function is executed when the GPI input
signal is driven High.
Tally Overview
When configured as a Tally, a port becomes an output, providing a status indicator. Typically this
is used to indicate which input(s) are on-air at any given moment. Each tally output on the card
can be configured to be active when any of the four inputs are on air. They can be configured as
Active High or Active Low. The Trigger type (Edge or Level) is only relevant for GPI inputs and
has no effect on Tally outputs. The tally outputs defaults to a logical high level when inactive.
When the tally becomes active, for example the signal is on-air, then the output is driven low.