Westermo ID-90 - Manual (Page 9)

9 6607-2204
• Extended Passive Bus. The difference between the short passive bus and the extended
passive bus is that the extended passive bus specifies a distance between the units, d3 and
that the units are located at the far end from the NT at a distance of d3 from the far end
terminating resistor TR. The range of d3 is from 25 to 50 m giving at least d1 =500 m.
(d2 see Short Passive Bus).
Diagram specifies practically achievable cable lengths as function
of cable capacitance for a 0.3 mm
2 wire.
1 2 3 4 5 6 7 8 9
ID-90
d
2
d
1
d
3
GR 4 Fax
1 2 3 4 5 6 7 8 9
ID-90
TA TE
NT
TA
Extended Passive Bus
Max 8 TA/TE
TR TR
Cable capcitance [pF/m]