RTS SSA-424A User Manual

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4-Wire Call Signal Connections
Call Signal Connections for other 4-wire 
Communications Systems
4-wire Call Send and Call Enable/Inhibit
The SSA-424A accepts a switch-contact input from the 
4-wire system and then generates a call signal output to the 
2-wire system. The SSA-424A also accepts an optional 
switch contact input to enable or inhibit call signaling 
between the 4-wire and 2-wire systems. Figure 6 shows the 
typical connections.
4-wire Call Receive
The SSA-424A receives call signals from the 2-wire system, 
then converts this to relay contact closure for use as a 4-wire 
call receive indication. The SSA-424A also provides +5 
VDC which can be connected to the relay contacts to 
generate a DC output signal instead of a contact closure. 
Connections for a simple contact are shown in Figure 7 on 
page 12. 
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a. Dependent on UIO-256 DIP Switch SW1 Settings for Input/Output Range as summarized in the UIO-256 manual.
TABLE 3. 
UIO-256 GPI Outputs Connector (J5)
GPI OUTPUT NUMBERS
a
RELAY CONTACT PIN NUMBERS
UIO-256 
FRAME #1
UIO-256 
FRAME #2
UIO-256 
FRAME #3
UIO-256 
FRAME #4
NORMAL 
CLOSED (NC) 
CONTACT
COMMON 
CONTACT
NORMAL 
OPEN (NO) 
CONTACT
FIGURE 6. Typical call send and call enable/inhibit connections for 
a 4-wire intercom system.