Vizio CPU-56 - Manual (Page 10)

WIRING FOR TIELINE CONNECTION OF THE EXCHANGES
Each exchange can be connected by means of a cable with a diameter
of 0.65mm for a distance of up to 2km.
Regarding the tieline links which are not used, turn off the
DIP switch of each unused tieline link inside the Tieline Unit TI-52.
Connect "T" line (2 wires) of the 4 wires of each link to "R" line
(2 wires) of the other exchange.
The 2 wires of the "T" line and "R" line have no polarity.
If the BOX-064 is used, its terminals No. 1 and 2 are for the
"R" line and No. 3 and 4 are for the "T" line.
1. Wiring for tieline connection of 2 exchanges
Exchange B
EX-2B
Exchange A
EX-2A
Tie line unit TI-52 Tie line unit TI-52
Note 1. Any combination of tieline links between exchanges "A" and
"B" is possible. But, in consideration of possible increase
in the number of exchanges to be connected from 2 to 3 in the
future, we suggest you connect TL (link No. 0, 1, 2, 3) of
exchange "A" to TH (link No. 4, 5, 6, 7) of exchange "B".