Appendix F
NT620S/NT620C Internal Processing
298
S
Number of words for screen element registration
The number of words used for screen element registration is as follows.
Allocated words:
Number of words
Allocated bits:
Number of words calculated by summing the number of bits in each area and taking 1 word
to be 16 bits.
Example:
Character string memory tables:
3 of 12 allocated words each
Numeral memory tables:
4 of 2 allocated words each
Allocated bits for control:
19 I/O relays, 7 link relays (contiguous bits)
The number of words assigned to character string memory tables and numeral memory tables is as follows:
12 words
3 + 2 words
4 = 44 words
The assignment for bits is as follows:
19 I/O relays/16 = 1 word with a remainder of 3 bits
→
2 words
7 link relays/16 = 0 words with a remainder of 7 bits
→
1 word
The total is therefore 44 words + 2 words + 1 word = 47 words
Elements occupying up to approximately 120 words, calculated in this way, can be registered. If the number of
elements is larger than this, internal processing is increased in proportion to the excess number and this gener-
ates a delay in processing.
If the point where the quantity that can be registered is exceeded is in the middle of an element that spans sever-
al words (for example a character string memory table), registration is quit without registering that element.
If there are bit memory tables that have been set to be read continuously, the requirement for this processing is
also registered. If the number of such bit memory tables is large, processing will be delayed.
S
Order of priority for registration
Elements are registered in the following order of priority according to their type.
(1) Allocated words of the PT status control area
(2) Allocated bits for control (lamps, lamp bits of touch switches, bit memory tables)
(3) Allocated words of numeral memory tables
(4) Allocated words of character string memory tables
If there is more than one element for each of (2) through (4), the elements are registered in accordance with the
following priority of word and bit areas:
(1) Data memory (DM)
(2) I/O relays (CH)
(3) Timers (TIM)
(4) Counters (CNT)
(5) Holding relays (HR)
(6) Auxiliary relays (AR)
Within each area, words and bits are allocated from the smallest number up.
Summary of Contents for NT620C
Page 1: ...Cat No V033 E1 5 Programmable Terminals NT620S 620C OPERATION MANUAL...
Page 2: ...NT620S 620C Programmable Terminals Operation Manual Revised April 2001...
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