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6GT2 097-3AH00-0DA2
2.4.2
Power supply
The cable between the ASM 421 and the SLG read/write device is a 6-core shielded cable, of which 4
cores are dedicated to the data interface and 2 to the power supply for the SLG read/write device. The
maximum length of the data cables can, depending on the physical interface, be anything up to 1000 m.
The maximum permitted cable run is generally shorter if the 24 V supply for the SLG read/write device is
used by the ASM 421. The maximum cable length also depends on the level of voltage drop. The following
table gives an overview of permitted cable lengths:
Con-
Con-
Resis-
ductor
ductor
tance
W
cross-
dia.
/km *)
section
[
mm]
[
2
mm
]
0.07
0.3
550
0.2
0.5
185
0.5
0.8
70
0.8
1.0
50
1.5
1.4
24
*) The values for resistance are average values and relate to the feed and return conductors. An individu-
al conductor has half the quoted resistance.
If cable runs longer than those specified in the table are used, the 24 V supply for the SLG read/write
device must not be used by the ASM 421. Instead, a 24 V supply must be fed directly to the SLG. (See
manual for configuration, installation and service; chapter 3.10; cable and connector allocation.)
Highlighted field:
The standard shielded LiYCY 6 x 0.25 cable recommended by SIEMENS. This cable is available from
SIEMENS under the order number 6GT2090-0A...
24 V supply to ASM 421:
The maximum length of the power supply cable for the ASM 421 is restricted to 20 m. If a longer cable is
used, or several ASMs are supplied from a single cable, the voltage drop on the supply cable to both
the ASM 421 and SLG read/write device must be taken into account. If necessary, the cross section of
the supply cable should be increased.
1
) According to length code
Subject to change without notice!
RD: 03/02
J31069-D0142-U001-A0-7618
SLG 40 / SLG 41
SLG 42 (I=180 mA)
(I=90 mA)
Max. cable length when
Max. cable length when
U
= 24 V
U
= 30 V
U
= 24 V U
V
V
V
120
240
40
360
720
120
950
1000
310
1000
1000
440
1000
1000
920
– 12 –
ASM 421 Technical Description
SLG 43 (I=250 mA)
Max. cable length when
= 30 V
U
= 24 V U
= 30 V
V
V
V
100
30
70
300
85
210
790
230
570
1000
320
800
1000
660
1000
1)
.
6GT2 002-0DA00
6GT2 002-0DB00
6GT2 002-0DC00
SLG 44 (I=80 mA)
Max. cable length when
U
= 24 V U
= 30 V
V
V
90
200
250
650
700
1000
1000
1000
1000
1000
ASM 421 / V.24
ASM 421 / RS422
ASM 421 / TTY
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