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Harris ADC Device Server User’s Guide
7-2 Switch-Only Device Configuration
Switch-Only Device Parameters
The Switch Only device parameters configure the ADC Device Server to switch to a switcher
crosspoint and/or trigger a GPI (general purpose interface) contact closure. GPI is an option
to the standard ADC Device Server system (requires a GPI board to be installed in the Device
Server).
Switch Only devices are used to:
◆ Incorporate material from external sources, such as network and satellite feeds, cameras and
presenters;
◆ Trigger events involving devices not supported by RS422 or RS232 protocols, through a GPI
(general purpose interface).
A Switch Only event inserted in a list can be set up to switch a crosspoint, count down a
predetermined amount of time and roll the next event. By entering Auto Upcount for the
event associated with a Switch Only device, the event counts down to zero and then holds the
list while counting up. A live feed can be switched away from by issuing a Play or Skip
command to the transmission list. This is done manually, through the control panel.
When a primary event in a list has an ID that matches the ID of the Switch Only device, the
event and device become associated (if the Switch Only device is assigned to the list). The
event goes through the transmission process like other types of events. The event (and device)
goes through preroll, switches at the end of preroll, counts down a duration, rolls the next
event and then goes through postroll. You can also Skip the event and roll the next event.
A Switch Only device can be used as a secondary event which is bound to another event. A
secondary event can close a GPI relay at a designated time before or after the primary event
goes to air. The duration of the closure can be controlled directly by the event. The event can
also be used to tag a primary event with a video overlay (such as a station bug) or generate a
tone at some predetermined time before entering a commercial break or returning to program
material. This type of usage requires an external device that is controlled by a GPI closure.
Many such devices are available on the open market.
There are two types of secondary GPI events that can be put on a list to control physical
contact closure – GPI Contact or Back-Timed GPI. The type of GPI you use depends on the
timing of the secondary event. GPI Contact runs a contact after the primary event runs. Back-
Timed GPI runs a contact before the primary event runs. Both GPI events are associated with a
Switch Only device whose ID matches the ID of the secondary event.
Switch Only events with the same ID may be played back to back as primary events. There are
no restrictions as long as these events are both primary events. Since Switch Only events have
no SOM, these events are always contiguous and will always play back to back.