Data Manipulation
Appendix B
B4
In Figure B.1, the Level 4 address is 260 (decimal), which is too large to
fit in one byte. Therefore, a byte of all ones is used to delimit the
two-byte address field for this level. The value 260 is then coded low
byte first. Note that the last level (Level 6 in this case) must be specified
in the address field even though it is equal to the default value of zero.
Figure B.1
Example of PLC3 Logical Addressing
>
PLC3 Extended Addressing
Level 1
Level 2
Level 3
Level 4
Level 5
Level 6
E3 .
2 . 0 . 260 . 0
0 .
Logical Addressing Format
0
0
6
5
1
1
4
3
0
1
2
1
0
0
0
0
0
0
0
0
1
0
1
1
1
1
1
1
1
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
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, 5,
and 6 are specified in the bytes that follow. Default values are used for
Levels 1, 2, and 4.
Level 1
Level 2
Level 3
Level 4
Level 5
Level 6
(Default = 3 for Data Table)
Byte 2
Is the value of the Level 3 address.
Byte 5
Is the high byte of the Level 5 address. Note that Bytes 4 and 5 together give
a value of 260 for the Level 5 address.
Byte 3
Is a delimiter that says the next two bytes are one address.
Byte 4
Is the low byte of the Level 5 address .
(Default =
Current Context
)
(Value = 2)
(Default = 0)
(Value = 260)
(Value = 0)
Zero
Flag Bit for Level:
Byte 6
Byte
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.