Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL User Manual
Page 82
4–34
Planning an Application
Publication 2706-817
Signed and Unsigned Integers
Data in signed and unsigned integer format occupy one word
(2 bytes or 16 bits) of memory, no matter how small the value is.
Every bit has a value that depends on its position in the word. The
value encoded is the sum of the bits that are set.
0
0
0
0
0
0
0
1
0
0
0
1
0
1
0
1
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
256
16
4
1
+
+
+
= 277
Unsigned Integer
1
1
1
1
1
1
1
0
1
1
1
0
1
0
1
Signed Integer
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
1
256
16
4
+
+
= –277
+
1
Sign Bit
1=Negative
0=Positive
2’s
Complement
BCD
Data in BCD format (also called 4-BCD) occupy one word of
memory. Every four bits encodes a single decimal digit 0
! 9.
0
0
0
0
0
0
1
0
0
1
1
1
0
1
1
BCD
1
2
4
8
1
1
2
4
8
1
2
4
8
1
2
4
8
2
7
7
0
= 277
Character Array
Data in Character Array format are assigned to ASCII variables. The
length of a character array is from 1 to 32 bytes.
The ST file type is a character array. Other file types can also be
viewed as characters.