Values And Constants; Floating-Point Numbers; Strings; Input Relays - Delta Electronics AH500 Operation Manual

A H 5 0 0 O p e r a t i o n M a n u a l

5.2.1 Values and Constants

Name
Bit
Nibble
Byte
Word
Double word
Quadruple word
The relation among bits, nibbles, bytes, words, and double words in the binary system is shown below.
W 1
BY 3
N B7 N B6 N B5
b31b30 b29 b28 b27 b26 b25 b24b23 b22 b21 b20b19 b18 b17 b16 b15 b14 b13 b12 b11 b10

5.2.2 Floating-point Numbers

The floating-point numbers are represented by decimal points in ISPSoft. For example, the floating-point
number of 500 is 500.0. Please refer to section 2.2.2 in AH500 Programming Manual for more information.

5.2.3 Strings

What strings can process are ASCII codes. A complete string begins with a start character, and ends with an
ending character (NULL code). If what users enter is a string, they can enter 31 characters at most, and the
ending character 16#00 will be added automatically in ISPSoft. Please refer to section 2.2.3 in AH500
Programming Manual for more information.

5.2.4 Input Relays

Function of the input

The input is connected to the input device (e.g. external devices such as button switches, rotary switches,
number switches, and etc.), and the input signal is read into the PLC. Besides, contact A or contact B of the
input can be used several times in the program, and the ON/OFF state of the input varies with the ON/OFF
state of the input device.
Input number (the decimal number):

For the PLC, the input numbers start from X0.0. The number of inputs varies with the number of inputs on
the digital input/output modules, and the inputs are numbered according to the order in which the digital
input/output modules are connected to the CPU module. The maximum number of inputs on the PLC can
reach up to 8192, and the range is between X0.0 and X511.15.
5 - 6
A bit is the basic unit in the binary system. Its state is either 1 or 0.
A nibble is composed of four consecutive bits (e.g. b3~b0). Nibbles can be
used to represent 0~9 in the decimal system, or 0~F in the hexadecimal
system.
A byte is composed of two consecutive nibbles (i.e. 8 bits, b7~b0). Bytes can
be used to represent 00~FF in the hexadecimal system.
A word is composed of two consecutive bytes (i.e. 16 bits, b15~b0). Words can
be used to represent 0000~FFFF in the hexadecimal system.
A double word is composed of two consecutive words (i.e. 32 bits, b31~b0).
Double words can be used to represent 00000000~FFFFFFFF in the
hexadecimal system.
A quadruple word is composed of four consecutive words (i.e. 64 bits,
b63~b0). Quadruple words can be used to represent 0000000000000000 –
FFFFFFFFFFFFFFFF in the hexadecimal system.
D W
B Y2 BY 1
N B4 N B3
Description
W 0
B Y 0
N B2 N B1 N B0
b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
D ouble w ord
W ord
B yt e
N ib ble
B it