Retentive Markers; Numeric Formats - Eaton easyE4 series Manual

5. Programming on the device
5.3 Circuit diagram elements
132
via the first 12 marker bytes (MB), 6 marker words or 3 marker double words. This will
generate undefined states. When write accesses are made successively within an MD,
such as to MD1, MW2, MB4 or M32, the last write operation is retained.
Observing the following wiring rules will prevent the double assignment of
marker bits.
For easyE4 with the marker bits M01-M96 use
Marker bytes, starting at MB13
Marker words, starting at MW07
Marker double words, starting at MD04

Retentive markers

You can declare a freely definable contiguous range between marker bytes as retent-
ive.
Device
easyE4
For more information on how to configure retentive markers in order to save data in a
non-volatile manner, please refer to → Section "Retention function", page 473

Numeric formats

The values of the data types marker byte (MB) and marker word (MB) are processed
as unsigned. In order to store negative values, you must use a marker double word.
This fact must be particularly taken into account if the output of a function block can
take on a negative value. You must temporarily store this value in a marker double word
in order to transfer it to the input of a function block, otherwise the sign information will
be lost.
The easyE4 device processes calculations with a signed 31-bit value.
The value range is: –2147483648 to +2147483647
In the case of a 31-bit value, the 32nd bit is the sign bit.
Bit 32 = status 0 -> positive number.
Bit 32 = status 1 -> negative number.
Example
00000000000000000000010000010010
11111110110111001111010001000111
easyE4 11/18 MN050009 EN www.eaton.com
Marker range that can be declared as retentive
MB01 - MB400
= 412 = 1042
bin hex
= FEDCF447
bin hex
dez
= –19073977
dez