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6.11 Clock / Calendar
X3M is equipped with a clock/calendar provided with a 15 years buffer battery.
It is updated when manufactured with the Europe/Rome time and time zone The clock/calendar is
equipped with the time zone managing functions.
It manages the automatic change from Standard Time to Daylight Saving Time and vice versa
6.11.1 Clock Format
The following Times are programmed”:
Coordinated Universal Time (UTC):
previously known as GMT (Greenwich Mean Time): it is the
universal time, shared by any earth location
Standard Time:
it is the local time of a specific time zone, based on the sun cycles (known as
Standard Time
Daylight Saving Time
it is the local time of a specific time zone
when an offset on standard time is
valid (DST offset). The introduction of this offset allows to increase the natural light duration in
the summer evenings.
Wall time:
it is how we refer to the clock time in ach time zone. The Wall time is equal to Daylight
Saving Time or to Standard Time according to weather an offset on sun cycle time is occurring
or not.
The difference between Standard Time and UTC time is named GMT offset.
Summarizing:
GMT offset = UTC – Standard Time
Wall Time = Standard Time + DST offset = UTC + GMT DST offset
The instrument RTC stores the following time information:
•
Date/time
•
UTC;
•
It identifies the time zone it belongs to.
X3M, starting from the UTC time can autonomously calculate the local time (Wall Time) of any place on
earth
The zone it belongs to is indicated to the instrument through a numeric index (time zone index) either on
the display or on a MODBUS register.
6.12 Memory
Non volatile data memory without buffer battery, capable to store data for more than 15 years.
It is structured as a disk with file system and directory and it can be accessed via Modbus protocol.
6.12.1 Dimensions
2 Mbytes Flash Disk
2.088.960 bytes available space
Organized in 4096 allocation units from 510 bytes each.
As each file occupies at least an allocation unit, a maximum of 4096 files can coexist on disk
6.12.2 Memory Read/Write.
Disk access via Modbus functions.
“Write General File”.
“Read General File”.
The data on disk are organized in record files, as per ModBus standard
6.12.3 File Structure
Each file is individualized by a numeric index of 2 bytes (FILE NUMBER, from 0 to 65535).
It can contain max 10000 records, addressed from 0 to 9999.
Each record can be max 238 bytes.
