Specifications
6
 Table 1 
  Dialing Scheme 
Dialing Scheme 
Zone Code  Zones 
00 All Call 
01 - 68  Individual Zones 
71 - 87  Fixed Zone Groups 
91 - 99  Logical Zone Groups 
  Note: Zone Code is the splitter zone DTMF tone. 
All splitters must use the same CLASS of wiring (CLASS “A” or “B”) for the audio output zones. See the 
SP4-APS Installation Instructions (P84577) for proper wiring of these zones. 
Individual Zone and Fixed Zone Group sequence numbers are controlled by the placement of the splitters 
in the RS485 digital communication circuit. The first splitter connected to the RS485 digital control port on 
the SP4-TZC will be assigned the first zone codes (Individual Zone codes of “01” and “02” for CLASS 
“A”, Individual Zone codes of “01” through “04” for CLASS “B”, and a Fixed Zone Group code of “71”). 
Using the previous example where the first splitter covers the warehouse area, let’s add a second splitter 
covering the front office area. If the paging zones are set for CLASS “A” then the warehouse will have 
Individual Zone codes of “01” and “02”. The front office area Individual Zone codes will be “03” and “04”. 
The Fixed Zone Group code for the warehouse will be “71”, and the front office Fixed Zone Group code 
will be “72” 
INDIVIDUAL 
ZONE CODES = 
01,02
FIXED ZONE 
CODE = 71
INDIVIDUAL 
ZONE CODES = 
03,04
FIXED ZONE 
CODE = 72
INDIVIDUAL 
ZONE CODES = 
05,06
FIXED ZONE 
CODE = 73
INDIVIDUAL 
ZONE CODES = 
07,08
FIXED ZONE 
CODE = 74
INDIVIDUAL 
ZONE CODES = 
09,10
FIXED ZONE 
CODE = 75
SP4-TZC
SP4-APS
SP4-APS
SP4-APS
SP4-APS
SP4-APS
SP40/2
SPB-160
SPB-160
#1
#2
#3
#4 #5
RS485
RS485
RS485
RS485 RS485
TO ADDITIONAL 
SP4-APS SPLITTERS
CONNECT THE SP4-TZC RS485 CONNECTION 
TO THE SP40/2 SP4-APS FIRST. 
Figure 1 
RS485 Communications Path from SP4-TZC to Last CLASS “A” Splitter 
Figure 1 shows the path of the RS485 digital control loop and the sequence of the splitters in that loop. The 
SP40/2 splitter is always
 the first splitter connected to the RS485 loop. Notice on Figure 1 that the 
individual and Fixed Zone Group codes are listed for a CLASS “A” splitter configuration. The SPB-160 is 
used as an example of an audio booster. 










