Four wires connect the two together. Vcc, Ground, SCL, SCA. There is a usb socket for 5v power to the unit.
DCC-EX CSB1 DCC Command Station
MECCANO HORNBY DUBLO ACHO & HORNBY JUN 1962 PRICE LIST EX+ 16/662/100 4P
MECCANO TOYS OF QUALITY FEB 1956 PRICE LIST EX+ 16/156/100M DUBLO DINKY HORNBY
Peco SYH 17 The Railway Modeller Book Introducing DCC New 16 page Booklet 2nd Po
