Micromod Micro-DCI: 53SL5100A Single Loop Controller Manuel d'utilisateur télécharger pdf (Page 138)

Single Loop Process Controller Instruction Manual

130 Communications

B.1.5 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 data type)

and data byte (e.g., B, C, H, and A data types) memory location determination.

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 described in Table B-3

should be applied for this instrument..

✎ Note Numbers used in this section that are expressed in hexadecimal

notation (base 16) are identified with an H after the number.

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

. 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 c o m p l e m e n t p o s i t i v e ,

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.

1 2 ... 133 134 135 136 137 138 139 140 141 142 143 ... 151 152

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