Manual

53ML5100A Manual Loading Station
Supplement to the Instruction Bulletin
Datalink Communications 11
4.2 CALCULATING DATA ADDRESSES
If communications software must be generated to accommodate unique Datalink applications require-
ments, then the instrument memory address scheme must be known for proper data bit (e.g., L datapoints)
and data byte (e.g., B, C, H, and A datapoints) memory location determination.
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 described in Table 4-2
should be applied for this instrument.
✎ Note Hexadecimal (base 16) numbers used in this section are identified
with a subscript
H
after the number.
Table 4-2. 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
.