ABB ControlIT 53MC5000 - B.1.5 Calculating Data Addresses

B.1.5 CALCULATING DATA ADDRESSES
If communications software must be generated to accommodate unique Datalink applications re-
quirements, then the controller memory address scheme must be known for proper data bit (e.g., L
data type) and data byte (e.g., B, C, H, and A data types) memory location determination.
Note: Numbers used in this section that are expressed in hexadecimal notation (base 16) are iden-
tified with a subscript
H
after the number.
This memory address scheme applies only if a
6
is in memory address location 8002
H
. Memory
address location 8002
H
must be read and if it contains a
6
, then the address scheme that is de-
scribed in Table B-3 should be applied for this controller.
Table B-3. Controller Memory Address Scheme
Data
Type
Base
Memory
Address
Byte
Size
Data Format Address Calculation Algorithm
B200
H
1 Represents a positive integer
with values from 0 to 255.
Address = B Base + (B Number)
= 200
H
+ (B Number)
Address example: B012 location
= 200
H
+ 12
D
= 200
H
+ C
H
= 20C
H
L500
H
1 Bit A single binary bit with a logical
value of 0 or 1. L datapoints
are packed 8 to a byte.
Address = L Base + (L Number/8)
= 500
H
+ (L Number/8)
Remainder = bit position in byte
Address example: L014 location
= 500
H
+ 14/8 = 501
H
, bit 6
(remainder).
C600
H
3 Represents floating point values
that have a resolution of one
part in 32,768 (15 bits) and a
dynamic range of
±
10
38
. The
first two bytes represent a 2’s
complement notation in
fractional form (2
-n
) whose
absolute value is between 0.5
and 0.9999. The third byte is
the power of 2 in 2’s
complement notation. Floating
point example:
64
H
00
H
07
H
= 100
D
(Decimal)
64
H
= 0110 0100, fractional
binary weights left to right are 0
= 2’s complement positive,
1 = 2
-1
= 1/2 = 0.5, 1 = 2
-2
=
1/4 = 0.25, 0=0, 0=0, 1 = 2
-5
=
1/32 = 0.03125, 0=0, and 0=0.
64
H
= 0.5+0.25+0.03125 =
0.78125. 07
H
= 128
D
. 128
D
X
0.78125
D
= 100.
Address = C Base + (3 X C Number)
= 600
H
+ (3 X C Number)
Address example: C011 location
600
H
+ (3 X 11) = 600
H
+ 33
D
= 600
H
+ 21
H
= 621
H
.
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53MC5000 Process Control Station
B-6