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2-2SectionAreas for Control/Notification

Reference:  The NT21’s clock function is not a counter. This function just displays the most

recent clock data read from the host.

 After the NT21 is turned ON, the default date and time (01/01/00 00:00:00) will

be displayed if the data in the PT is not correct until the clock data is read prop-

erly from the host.

 The clock function does not strictly check the date and day of the week settings.

The data must therefore be set correctly so that there is no discrepancy be-

tween the date and the day of a week

 The clock data cannot be set from the NT21’s System Menu or the NT Support

Tool.

 The clock data is always BCD regardless of the setting of the Storage Type set-

ting made in the PT configuration settings from the Support Tool.

The PT periodically reads the contents of the Clock Data Area to update the

clock data in the PT.

The structure of the clock data in the PT is the same as the structure of the words

containing the clock data in the CS/CJ-series and C-series PCs. If these words

are allocated for the Clock Data Area with the NT21, then the clock data will be

automatically synchronized during operation if the words are allocated.

If the structure of the clock data in the host is not the same as the structure in the

PT (or the words containing the clock data in the host cannot be allocated), use

the ladder program to update the Clock Data Area periodically, e.g., by copying

the contents of the PC’s clock data to the Clock Data Area.

Reference: Numeral memory table entries 247 to 253 are reserved for the clock function

(read-only) and the clock data is automatically stored in them. Refer to 3-10 Dis-

play and Setting of Calendar Clock for the methods used to display the date or

time.

Clock Data Area

Functions

Omron NT21 User Manual

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