Twisted-pair connections, Figure 8. wire connections to the i/o box, And utp for rs-422), if desired. see – Interlogix KTD-405 Series User Manual User Manual
Page 17

Chapter 2
Installation
13
Twisted-pair connections
The twisted-pair connections are available to connect additional devices or for existing installations where 
individual wires were used to connect to the old phone-style I/O box. Easy-to-use RJ-cable connections are 
also available on the new I/O box. See 
Adhere to all installation guidelines while making connections, including your local codes and those provided 
in 
Figure 8. Wire connections to the I/O box
Bias switch
The bias switch maintains an appropriate load on the RS-485 line. Set the bias switch to ON for one 
keypad in a typical system (any one keypad and only one keypad). If your system is divided into 
groups that are separated by fiber or Ethernet bridges, you must set the bias switch to ON for one 
keypad in each group.
Tie-wrap
For safety, use a tie-wrap 
to secure the power cable 
to the tie-in.
Observe polarity for:
• 12 VDC
• RS-422
• RS-485
Earth ground
(to ground)
RS-422 IN
(from keypad or
alarm unit, if used)
Speaker/shield
(to remote
speaker, if used)
*
For mux, DVMRe, or additional keypad I/O box. (RS-485 
connections are also available with the RJ45 connectors.) 
RS-485 connection*
RS-422 OUT
(to switcher
or cameras)
12 VDC power
 (12 VDC transformer must 
have a positive center 
polarity plug 
)
