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Note: The total length of the cable must be limited to 1200 metres although the calculation
result is 1432 metres.
Table 15 Maximum display units cable length
Cable
Wire Resistance R
Type
at 20° C
c.s.a. of cable = 1.5mm²
1728
Unit
I
(A)
0.088
unit
V
(V)
12
batt
Allowed
Max.
cable
distance
No. of
resistance
from
units
R
CIE, D
allowed
(Ω)
(metres)
16
8.52
716
15
9.09
764
14
9.74
819
13
10.49
881
12
11.36
955
11
12.40
1042
10
13.64
1146
9
15.15
1200
8
17.05
1200
7
19.48
1200
6
22.73
1200
5
27.27
1200
4
34.09
1200
3
45.45
1200
2
68.18
1200
1
136.36
1200
Table 15 was tabulated based on the calculation example given previously under the same
conditions described above. This pre-calculated table serves as a quick estimate for the
cable length to the number of Display Units that can be used depending on the selected
cables.
If a cable with a reduced conductor area is used the wire resistance (Ω / Km) will be higher
and the possible cable length will be shorter. The
communications standard. Therefore, the maximum distance from the CIE. for any number
of Display Unit should not exceed 1200 metre even though calculations show otherwise.
BAC0898
u
11.9
Ω/Km
1736
0.079
12
Allowed
Max.
cable
distance
resistance
from
R
CIE, D
allowed
(Ω)
(metres)
9.49
798
10.13
851
10.85
912
11.68
982
12.66
1064
13.81
1160
15.19
1200
16.88
1200
18.99
1200
21.70
1200
25.32
1200
30.38
1200
37.97
1200
50.63
1200
75.95
1200
151.90
1200
173
Technical/Programming Manual
FT1020G3 Rev 2.2.1
SMA2704
Wire Resistance R
u
at 20° C
c.s.a. of cable = 1mm²
1728
0.088
12
Allowed
Max.
Allowed
cable
distance
cable
resistance
from
resistance
R
CIE, D
R
allowed
(Ω)
(metres)
9
406
9
433
10
464
10
500
11
541
12
590
14
649
15
722
17
812
19
928
23
1082
27
1200
34
1200
45
1200
68
1200
136
1200
display units RS485 bus
21
Ω/Km
1736
0.079
12
Max.
distance
from
CIE, D
allowed
(Ω)
(metres)
9
452
10
482
11
517
12
556
13
603
14
658
15
723
17
804
19
904
22
1033
25
1200
30
1200
38
1200
51
1200
76
1200
152
1200
uses RS485
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