Network and application layer protocols chapter 12 – Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual User Manual
Page 160
Network and Application Layer Protocols
Chapter 12
12Ć13
Figure 12.5
Example of PLC-3 Logical Addressing Format
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10066–I
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PLC–3 Extended Address
Data Table Area = Level 1
Context = Level 2
Section = Level 3
File = Level 4
Offset = Level 5
Word = Level 6
Logical Addressing Format
Always zero
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Level 1 (Default = 3 for date table)
Level 2 (Default = 1 for current context)
Level 3 (Value = 2)
Level 4 (Default = 0)
Level 4 (Value = 260)
Level 5 (Default = 1)
Level 6 (Value = 0)
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 the levels 1, 2, and 5.
Byte 2 –– is the value of the level–3 address.
Byte 3 –– is a delimeter that says the next two bytes are one address.
Byte 4 –– is the low byte of the level–4 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 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.
E3 . 1 . 2 . 260 . 0 . 0
Flag bit for level: