Ir (Internal Relay)Area - Omron SYSMAC C2000H Operation Manual

IR Area
Digit number
Bit number
Contents
Converting Different Forms
of Data
Decimal Points
3-3

IR (Internal Relay)Area

18
tains four digits, which are numbered from right to left. These digit numbers
and the corresponding bit numbers for one word are shown below.
3
15 14 13 12 11
0 0 0 0 0
When referring to the entire word, the digit numbered 0 is called the right-
most digit; the one numbered 3, the leftmost digit.
When inputting data into data areas, it must be input in the proper form for
the intended purpose. This is no problem when designating individual bits,
which are merely turned ON (equivalent to a binary value of 1) or OFF (a bi-
nary value of 0). When inputting word data, however, it is important to input it
either as decimal or as hexadecimal, depending on what is called for by the
instruction it is to be used for. Section 5 Instruction Set specifies when a par-
ticular form of data is required for an instruction.
Binary and hexadecimal can be easily converted back and forth because
each four bits of a binary number is numerically equivalent to one digit of a
hexadecimal number. The binary number 0101111101011111 is converted to
hexadecimal by considering each set of four bits in order from the right. Bi-
nary 1111 is hexadecimal F; binary 0101 is hexadecimal 5. The hexadecimal
equivalent would thus be 5F5F, or 24,415 in decimal (16
x 5 + 15).
Decimal and BCD are easily converted back and forth. In this case, each
BCD digit (i.e., each group of four BCD bits) is numerically equivalent of the
corresponding decimal digit. The BCD bits 0101011101010111 are converted
to decimal by considering each four bits from the right. Binary 0101 is deci-
mal 5; binary 0111 is decimal 7. The decimal equivalent would thus be 5,757.
Note that this is not the same numeric value as the hexadecimal equivalent
of 0101011101010111, which would be 5,757 hexadecimal, or 22,359 in deci-
3
mal (16 x 5 + 16
Because the numeric equivalent of each four BCD binary bits must be nu-
merically equivalent to a decimal value, any four bit combination numerically
greater then 9 cannot be used, e.g., 1011 is not allowed because it is numeri-
cally equivalent to 11, which cannot be expressed as a single digit in decimal
notation. The binary bits 1011 are of course allowed in hexadecimal are a
equivalent to the hexadecimal digit C.
There are instructions provided to convert data either direction between BCD
and hexadecimal. Refer to 5-15 Data Conversion for details. Tables of binary
equivalents to hexadecimal and BCD digits are provided in the appendices
for reference.
Decimal points are used in timers only. The least significant digit represents
tenths of a second. All arithmetic instructions operate on integers only.
The IR area is used both as data to control I/O points, and as work bits to
manipulate and store data internally. It is accessible both by bit and by word.
Those words that are used to control I/O points are called I/O words. Bits in
I/O words are called I/O bits.
The number of I/O words varies between the C1000H and C2000H as shown
in the following table. As shown, the remaining words for each PC are work
2 1
10 09 08 07 06
0 0 0 0 0
2
x 7 + 16 x 5 + 7).
Section 3-3
0
05 04 03 02 01
0 0 0 0 0
3
x 5 + 16
00
0
2
x 15 + 16