7700FR/7800FR MultiFrame
7800TR-32x24 Modular Tally Router
Page - 14
Revision 1.2
3.6
GENERAL PURPOSE OUTPUTS
There are 32 General Purpose Outputs (GPOs) available on the two 62-pin D-Sub connectors on the
rear plate. The rear GPOs are “Dry”. The GPOs can be used to activate tally lights or send triggers to
equipment such as the Evertz VIP multiviewers, switchers, and keyers. They can also be used to drive
camera tally lamps. The pinout of these connectors is shown in Figure 3-4.
The General Purpose Outputs are not polarity sensitive. Each GPO has two pins marked “A” and “B”.
The GPO consists of an isolated relay contact. When the GPO is closed, the two contacts “A” and “B”
will be electrically connected to each other. See Figure 3-6 for the circuit diagram of a GPO. The GPO
specifications are listed in section 2.2.
Each GPO is protected against excessive current with a polyfuse. Polyfuses operate by means of
thermal limiting. The maximum allowable current is shown in Table 3-6. If excessive current is applied
to the GPO the polyfuse will heat up and open. This process happens very quickly if the current is high
but may take hours if the current is only a little above the maximum. When the polyfuse opens, it
immediately begins to cool and will eventually reset on its own. If the fault is not removed, the process
will repeat itself any may cause a “strobing” effect on some load devices connected to the GPO.
The currently selected Wet Power source is available on three pins of the D-Sub connector. The
WET+
voltage can be used to wire the GPOs as “Wet”. Please see section 0 for more information.
GPO A
GPO B
0.15A max
Relay
Figure 3-6: Rear General Purpose Output Circuit Diagram (Dry)
Maximum Current
0.15 Amps
Maximum Voltage
+/- 24V DC
Closed Contact Resistance
< 3.0 Ω
Table 3-6: Rear General Purpose Output Electrical Specifications
Do not exceed the maximum voltage specified or the GPO may be damaged.
