GRASS VALLEY KARRERA K-FRAME, Инструкция по установке и обслуживанию, Страница: 89 / 278

KARRERA K-FRAME — Installation & Service Manual 89
Video Processor Frame GPI/Tally Interface
GPI and Tally Connections
Each K-Frame Video Input module has a 50 pin female subminiature D con-
nectors on the rear of the chassis, available for GPI and tally. Each connector
has 8 GPI Inputs, 24 Tally Outputs, and 8 GPI Outputs. These connectors
do not share any signals in common, other than ground reference and
chassis ground. Because of this, some GPI/Tally interconnects may require
external common connections between connectors, as explained below.
GPI Inputs
The purpose of the GPI In pins is to provide a stimulus from the customer's
equipment to the switcher. A simple connection of two pins activates the
corresponding input. An external relay contact or an open-collector output
can be employed.
CAUTION When connecting to an open-collector output, there is no ground potential
isolation between the Video Processor Frame and controlling devices.
Since the circuit ground is led out of the device, cabling should be shielded
for this kind of control. Non-shielded cables may cause EMC and/or ESD
problems. To activate a GPI In you must provide switch closure between a
particular GPI In pin and one of the two GPI In Com pins (1 and 34). Pins 1
and 34 of each connector is connected to ground (
Figure 59 ). For applica-
tions that span across more than one connector, only one ground (common)
connection is required.