Parker HPD2N, Руководство пользователя, Страница: 64 / 125

Parker Hannifin S.p.A. - S.B.C. Division HPD N User’s Manual
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OPERATIONAL DESCRIPTION
The pico-PLC program is scanned every 6.144 msec; at each sampling first the inputs are
read, then the two timers are updated (Pr92 Pr93 b99.0 and b99.1), the user program is
scanned, and finally the outputs are updated. Therefore, reading of the inputs and output
updates can deviate temporally by up to 6.144 ms with respect to the physical event.
All pico-PLC instructions with the exception of mathematical instructions, operate on
single bits; moreover, available stack depth is a single bit.
Instruction LD (LDN) loads the bit defined as operand into the stack, while all other
logical instructions operate on the stack. Mathematical operations are executed only if the
stack bit is at 1.
The following logic operations truth tables are provided for the user’s convenience:
The relative inverted ANDN and ORN operations follow the same logic, except they use
the inverted value of the specified bit.
There are 8 bits with save facility from b90.8 to b90.15 reserved for the PLC; a further 8
bits from b91.8 to b91.15 are available for the PLC; these are not stored and are always at
zero at drive power-up.
Also 10 word parameters are reserved, specifically from Pr80 to Pr89 with save facility
and option for use as 5 double word parameters. For mathematical operations the pico-PLC
has 9 constants available, from Pr71 to Pr79 selected from those that are most frequently
utilised in standard applications.
When using mathematical instructions (ADD, SUB, MUL, DIV) note that operators are
assumed as words with their relative signs. If a double word operation is necessary, parameter
b94.0 must be set to 1 before the operation; after the operation the PLC will automatically set
the bit to zero. Parameters Pr60...Pr69 are considered as double words so an operation like
[ADD 71 72 64] will write the result -1 in the double word Pr64:65 without having to set
b94.0=1 before the operation. If Pr80=-1 and Pr81=0, the operation [ADD 80 72 64] will have
the result Pr64:65=-1, while the same operation performed with b94.0=1 will assume Pr81 as
the high part of the double word Pr80:81 so the result will be Pr64:65=65535. In the first case,
therefore, operands other than Pr60...Pr69 will be treated as words, while in the second case
they will be treated as double words.
Note that in mathematical operations on double words, operands and results are defined as
follows: the operand parameter defines the least significant part while the most significant
part is represented by the word with the next serial address (see chapter
Serial addresses and
parameter lengths ). Parameters from Pr50 to Pr69 and from Pr80 to Pr89 are successive.
logical AND operations
bit A bit B result
0 0 0
0 1 0
1 0 0
1 1 1
logical OR operations
bit A bit B result
0 0 0
0 1 1
1 0 1
1 1 1