Analog Input/Output Modules

Measured-Value Representation for Current Measuring Ranges from 4 to 20 mA

Current Limiting

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:

SA broken wire signal cannot be emitted.

SDetection of the overrange can be achieved by scanning bits 29 and 211.

SA broken wire can be detected with currents < 3 mA.

SIf 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

w4096

4095

3072

3071

2561

2560

2048

512

511

384

383

0

Input Cur- rent in mA

w32.000

31.992

24.0

23.992

20.008

20.0

16.0

4.0

3.992

3.0

2.992

0

 

 

Byte 0

 

 

 

 

 

 

Byte 1

 

 

 

 

 

7

6

5

4

3

2

1

0

 

6

5

4

 

3

2

1

0

 

7

 

 

S

211 210 29 28 27 26 25

24 23 22 21 20 A

E

OV

 

0

1

1

1

1

1

1

1

1

1

1

1

 

1

0/1

0

1

Overflow

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

1

1

1

1

1

1

1

1

1

1

1

 

1

0/1

0

0

Overrange

0

1

1

0

0

0

0

0

0

0

0

0

 

0

0/1

0

0

Short-circuit with two-

0

1

0

1

1

1

1

1

1

1

1

1

 

1

0/1

0

0

wire transducer

0

1

0

1

0

0

0

0

0

0

0

0

 

1

0/1

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

1

0

1

0

0

0

0

0

0

0

0

 

0

0/1

0

0

 

0

1

0

0

0

0

0

0

0

0

0

0

 

0

0/1

0

0

Rated range

0

0

0

1

0

0

0

0

0

0

0

0

 

0

0/1

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

0

0

0

1

1

1

1

1

1

1

1

 

1

0/1

0

0

Range

0

0

0

0

1

1

0

0

0

0

0

0

 

0

0/1

0

0

underflow

0

0

0

0

1

0

1

1

1

1

1

1

 

1

0/1

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

System Manual

9-71

C79000-G8576-C199-06

Page 453
Image 453
Siemens S5-135U/155U appendix Short-circuit with two