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Technical/Programming Manual
FT1020G3 Rev 2.2.1
173
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
Type
BAC0898
SMA2704
Wire Resistance R
u
at 20° C
11.9
Ω/Km
Wire Resistance R
u
at 20° C
21
Ω/Km
c.s.a. of cable = 1.5mm²
c.s.a. of cable = 1mm²
Unit
1728
1736
1728
1736
I
unit
(A)
0.088
0.079
0.088
0.079
V
batt
(V)
12
12
12
12
No. of
units
Allowed
cable
resistance
R
allowed
(Ω)
Max.
distance
from
CIE, D
(metres)
Allowed
cable
resistance
R
allowed
(Ω)
Max.
distance
from
CIE, D
(metres)
Allowed
cable
resistance
R
allowed
(Ω)
Max.
distance
from
CIE, D
(metres)
Allowed
cable
resistance
R
allowed
(Ω)
Max.
distance
from
CIE, D
(metres)
16
8.52
716
9.49
798
9
406
9
452
15
9.09
764
10.13
851
9
433
10
482
14
9.74
819
10.85
912
10
464
11
517
13
10.49
881
11.68
982
10
500
12
556
12
11.36
955
12.66
1064
11
541
13
603
11
12.40
1042
13.81
1160
12
590
14
658
10
13.64
1146
15.19
1200
14
649
15
723
9
15.15
1200
16.88
1200
15
722
17
804
8
17.05
1200
18.99
1200
17
812
19
904
7
19.48
1200
21.70
1200
19
928
22
1033
6
22.73
1200
25.32
1200
23
1082
25
1200
5
27.27
1200
30.38
1200
27
1200
30
1200
4
34.09
1200
37.97
1200
34
1200
38
1200
3
45.45
1200
50.63
1200
45
1200
51
1200
2
68.18
1200
75.95
1200
68
1200
76
1200
1
136.36
1200
151.90
1200
136
1200
152
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
display units RS485 bus
uses RS485
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.