Matrix-orbital PK202-24-USB Manual de usuario descargar pdf (Pagina 36)

8.3 On Numbers

Like all computerized devices, the display operates with commands and values in the form of binary

numbers. These binary numbers are arranged in 8 digit (i.e., 8 bit) groups called bytes. The decimal value

of a byte may have any value from 0 to 255.

Bytes are usually speciﬁed in either decimal or hexadecimal (base 16) form for convenience, since binary

numbers are confusing to deal with directly. Hexadecimal (hex) numbers are particularly convenient because

exactly two hexadecimal digits make up one byte, each hex digit representing 4 binary digits (4 bits) as shown

in the Table below.

Table 23: Hex Value Table

Binary Hex Decimal Binary Hex Decimal

0000 0 0 1000 8 8

0001 1 1 1001 9 9

0010 2 2 1010 A 10

0011 3 3 1011 B 11

0100 4 4 1100 C 12

0101 5 5 1101 D 13

0110 6 6 1110 E 14

0111 7 7 1111 F 15

Based on the table, the byte 01001011 can be represented in hex as 4B, which is usually written as any

of 4Bh, 4BH, 4B hex or 0x4B.

The numbers can be expressed in decimal form if preferred.

8.3.1 ASCII Characters

Since computers deal internally with numbers only, but externally with both letters and numbers, several

schemes were developed to ’map’ written characters to numeric values. One such scheme has become

universal; the American Standard Code for Information Interchange, or ASCII. ASCII tables are readily

available from a number of sources. A few examples will do here;

Table 24: Example of an ASCII Table

The letter A has a value of 65 decimal or 41 hex

The letter a has a value of 97 decimal or 61 hex

The number 0 has a value of 48 decimal or 30 hex

The number 9 has a value of 57 decimal or 39 hex

This gives rise to the possibility of confusion when parameters are being set on the display. For example,

the GPO ON and OFF commands use a number to indicate which GPO is being controlled. We’re told that

Matrix Orbital PK202-24-USB 32

1 2 ... 31 32 33 34 35 36 37 38 39 40 41 ... 47 48

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Matrix-orbital PK202-24-USB Manual de usuario Pagina 36