Siemens IP-Module Manual descargar pdf (Pagina 254)

IP 266 Communication Between the CPU and the IP 266

Binary-coded positions

15 bits are provided for the integer portion of the number. It is thus possible to

represent the number 2

- 1, or 32 767. In the case of a negative number, the

integer portion is represented as two's complement. The decimal digits are

specified as an absolute value.

BCD-coded positions

The sign is specified in bits 4 to 7 of byte 4. If the number is negative, bit 7, at

least, must be "1". Since there are three decimal places, four decades are still

available for the integer portion of the number.

Binary (KF fixed-point

constant format)

BCD (KH hexadecimal

constant format)

Integer positions Byte 4

Byte 5

Byte 4

Byte 5

Byte 6 (bits 4 to 7)

Decimal positions Byte 6

Byte 7

Byte 6 (bits 0 to 3)

Byte 7

Positions in the range 0 to - 0.999

Special rules govern the definition of a binary value between -1 and 0 (e. g. - 0.5).

These values have an integer value of - 0, which cannot be represented as two's

complement. When you want to specify a position in this range, you must enter

the values that make up the position in the following order:

1. Enter integer position "0" as a positive value in bytes 4 and 5.

2. Enter the decimal positions as a negative number in two's complement

representation in bytes 6 and 7.

A small negative number in BCD format is defined in the usual manner.

EWA 4NEB 812 6057-02

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Siemens IP-Module Manual Pagina 254