Siemens SIMATIC S5, Системное руководство

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Measured-value
representation for current
measuring ranges from 4 to
20 mA
Measuring range 500 mV; card with 31.25 ohm shunt
(6ES5 498-1AA51/AA71)
The 4 to 20 mA range is resolved to 2048 units at an interval of 512 to
2560. If you require a representation from 0 to 2048, you must
subtract 512 units by software. Please note the following:
••
A broken wire signal cannot be emitted.
••
Detection of the overrange can be achieved by scanning bits 2
9
and 2
11
.
••
A broken wire can be detected with currents < 3 mA.
Current limiting
••
If you short-circuit the positive and negative terminals of the
transducer when using the 6ES5 498-1AA51 range card (for a
two-wire transducer), the current is limited to about 28 mA. Until
the thermal current limiting circuit responds in the range card
(about 3 s), a short-circuit current of approximately 250 mA flows;
this sets the overflow bit for this duration at all channels.
Units Input
Current
in mA
7
S 6
2
11
5
2
10
4
2
9
3
2
8
2
2
7
1
2
6
0
2
5
7
2
4
6
2
3
5
2
2
4
2
1
3
2
0
2
A 1
E 0
OV
≥
4096
≥
32.000 0
1 1 1 1 1 1 1 1 1 1 1 1 0/1 0 1 Overflow
4095
3072
3071
2561 31.992
24.0
23.992
20.008
0
0
0
0 1
1
1
1 1
1
0
0 1
0
1
1 1
0
1
0 1
0
1
0 1
0
1
0 1
0
1
0 1
0
1
0 1
0
1
0 1
0
1
0 1
0
1
0 1
0
1
1 0/1
0/1
0/1
0/1 0
0
0
0 0
0
0
0 Overrange
Short-circuit with two-
wire transducer
2560
2048
512
20.0
16.0
4.0
0
0
0 1
1
0 0
0
0 1
0
1 0
0
0 0
0
0 0
0
0 0
0
0 0
0
0 0
0
0 0
0
0 0
0
0 0
0
0 0/1
0/1
0/1 0
0
0 0
0
0
Rated range
511
384
383 3.992
3.0
2.992
0
0
0 0
0
0 0
0
0 0
0
0 1
1
1 1
1
0 1
0
1 1
0
1 1
0
1 1
0
1 1
0
1 1
0
1 1
0
1 0/1
0/1
0/1 0
0
0 0
0
0 Range underflow
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0/1 0 0 Broken wire
A = Active bit
E = Error bit
OV = Overflow bit
S = Sign
Byte 0 Byte 1
The 465 Analog Input Module
System Manual
9 - 74
C79000-B8576-C109-03