Rockwell-automation 1770-KF2 Data Highway or Highway Plus Interface Mo Uživatelský manuál stáhnout pdf (Strana 153)

Data Encoding and Addressing

Chapter 6

6-16

PLC-3 and PLC-5

PLC-3 and PLC-5 controllers use physical addresses that are related to

logical addresses by means of pointers. Since no two PLC-3/PLC-5

systems are configured identically, the pointers are not fixed. Therefore,

there is no algorithm for converting logical to physical PLC-3 or PLC-5

addresses.

The PLC-3/PLC-5 physical address is a word address. It goes in the

4-byte field labeled “PLC-3 physical ADDR” or “PLC-5 physical ADDR”

in the PLC-3/PLC-5 physical read or write command message format

(Chapter 5). The format for this physical address field is:

PLC-3/PLC-5

Physical Address

First Byte

A24 A23 A22 A21 A20 A19 A18 A17

Second Byte

00000000

Third Byte

A8 A7 A6 A5 A4 A3 A2 A1

Fourth Byte

A16 A15 A14 A13 A12 A11 A10 A9

In this format, A1 through A24 represent the 1 to 24 bits of the physical

address value. For example, to address a command message to Physical

Word Address 12,200 decimal (002FA8 hex), you would use the

following binary code in the address field:

First

Byte

00000000(V

alue 00 Hex)

Second Byte

00000000

(Always 00 Hex)

Third Byte

10101000(V

alue A8 Hex)

Fourth Byte

00101111(V

alue 2F Hex)

The recommended procedure for uploading or downloading PLC-3 or

PLC-5 memory is to begin at Physical Address 0000 and proceed

sequentially to the end of memory. Since a single physical read or write

command can transfer only about 120 words of data, it will take many

such commands to upload or download the entire PLC-3 or PLC-5

memory. Therefore, each successive physical read or write should begin

at the next physical address after the one where the previous command

stopped.

1 2 ... 148 149 150 151 152 153 154 155 156 157 158 ... 234 235

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