Micromod Micro-DCI: 53IT5100A Indicator/Totalizer User Manual
Page 72
B.1.5 CALCULATING DATA ADDRESSES
If communications software must be generated to accommodate unique Datalink applications re-
quirements, then the instrument 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 identified with an H after the number.
This memory address scheme applies only if a 6 is in memory address location 8002H. Memory
address location 8002H 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 instrument.
Table B-3. Instrument Memory Address Scheme
Data
Type
Base
Memory
Address
Byte
Size
Data Format
Address Calculation Algorithm
B
200H
1
Represents a positive integer
with values from 0 to 255.
Address = B Base + (B Number)
= 200H + (B Number)
Address example: B012 location
= 200H + 12D = 200H + CH = 20CH
L
500H
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)
= 500H + (L Number/8)
Remainder = bit position in byte
Address example: L014 location
= 500H + 14/8 = 501H, bit 6
(remainder).
C
600H
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:
64H 00H 07H = 100D (Decimal)
64H = 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.
64H = 0.5+0.25+0.03125 =
0.78125.07H = 128D. 128D X
0.78125D = 100.
Address = C Base + (3 X C Number)
= 600H + (3 X C Number)
Address example: C011 location
600H + (3 X 11) = 600H + 33D
= 600H + 21H = 621H.
53IT5100 Indicator/Totalizer
B-6