Rockwell-automation 1770-KF2 Data Highway or Highway Plus Interface Mo Manual de usuario descargar pdf (Pagina 148)

Data Encoding and Addressing

Chapter 6

6-11

In Figure 6.7, the Level 5 address is 260 (decimal), which is too large to

fit in one byte. Therefore, a byte of all 1’s is used to delimit the 2-byte

address value for this level. The value 260 is then coded low byte first.

Note that the last level (Level 6 in this example) must be specified in the

address field even though it is equal to the default value of zero.

Figure 6.7

Example

of PLC-3 Logical Binary Addressing Format

PLC-3 Extended

Address

Level 1

Level 2

Level 3

Level 4

Level 5

Level 6

E3 . 8 . 260 . 0 . 0X.

Logical

Addressing Format

00 00 10 00

11 11 11 11

00 00 01 00

00 00 00 01

00 00 00 00

Always

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

Byte 1

Is the flag byte. In this case it indicates that the addresses for Levels 3, 4,

and 6 are specified in the bytes that follow

. Default values are used for

Levels 1, 2, and 5.

Level 1

Level 2

Level 3

Level 4

Level 5

Level 6

(Default = 3 for Data T

able)

Byte 2

Is the value of the Level 3 address.

Byte 5

Is the high byte of the Level 4 address. Note that Bytes 4 and 5 together give

a value of 260 for the Level 4 address.

Byte 3

Is a delimiter that says the next two bytes are one address.

Byte 4

Is the low byte of the Level 4 address .

(Default = Current Context)

alue = 8)

alue = 260)

(Default = 0)

alue = 0)

Zero

Flag Bit for Level:

Byte Byte 6

Is the value of the Level 6 address. Even though it is the default value, it must

be specified because it is the last level in the desired extended address.

Data

able

Area

Context

Section

File

Structture

Word

11261

1 2 ... 143 144 145 146 147 148 149 150 151 152 153 ... 234 235

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