2
0
1
8
-0
9
24
Appendix
5.2
Data Cables and Accessories
RS485 data cable
For the RS 485 data transfer path, a 4-wire, shielded, twisted pair data cable must be used.
One wire pair is used for the supply voltage, and one pair for the RS 485 data connection. The
maximum length of the cable depends on the data transfer capacity of the data cable (core-
core) and on the cross section of the cables for power supply of the WCS readers. For data
transfer, a small core cross section, and thus small cable capacitance is an advantage,
whereas for the power supply the largest possible cross section is required. The table below
shows the possible cable lengths depending on the cable cross section.
In the calculations, the worst case scenario was assumed: All WCS readers are located at the
end of the data line. In the case of large cable lengths, and when connecting multiple WCS2
readers with heating, 6-wire data cable (3 x 2) can be used. These data cables use 2 pairs for
the power supply (doubling the cable cross section), and one pair for the RS 485 data line.
The table shows the possible cable lengths depending on the cable capacitance (core-core).
The number of connected WCS readers is of no significance.
SSI data cable
For SSI data transfer, a 6-wire, shielded, twisted pair data cable (3 x 2) must be used. One wire
pair is used for the supply voltage, one pair for the CLK line, and one pair for the DATA line. The
cable lengths that are technically possible can be determined from the T tables.
Capacitance (core-
core)
RS485 interface
19.2 KB (LS246)
62.5 KB (LS221)
187.5 KB (LS211)
60 pF
500 m
500 m
300 m
90 pF
500 m
450 m
275 m
120 pF
500 m
400 m
250 m
Capacitance (core-
core)
SSI Interface
125 kHz
250 kHz
500 kHz
60 pF
200 m
100 m
30 m
90 pF
150 m
80 m
25 m
120 pF
100 m
60 m
20 m
Cable
cross
section
AWG
Number of WCS readers without
heating
Number of WCS readers with
heating
1
2
3
4
1
2
3
4
0.14 mm
2
~ 26
200 m
110 m
70 m
50 m
15 m
10 m
7 m
5 m
0.22 mm
2
~ 24
320 m
170 m
110 m
80 m
30 m
15 m
10 m
7 m
0.25 mm
2
350 m
190 m
130 m
90 m
35 m
17 m
12 m
8 m
0.28 mm
2
400 m
220 m
150 m
110 m
40 m
20 m
15 m
10 m
0.34 mm
2
~ 22
500 m
250 m
180 m
140 m
50 m
25 m
17 m
12 m
0.50 mm
2
~ 20
500 m
400 m
270 m
200 m
70 m
35 m
25 m
17 m
