Automation Direct D0-DCM, Руководство пользователя

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Getting Started
User Application
Guidelines
RLL
Programming
for Communications
4–6
RLL Programming for Communications
DL05/06 Data Communications Module, 1st Edition, 08/05
Addressing the Different Memory Types
Some data types are inherently 16 bits long, for example timer and counter current
values. Other data types are 1 bit long, for example: discrete inputs and outputs.
Word-length and bit-length data are mapped into Word Memory, also known as
V-memory, which allows you to address any of the different memory types as 16-bit
words.
Bit memory can be addressed in Read and Write instructions by the name of the first
bit of any byte. If your second LD instruction contains the constant K8, eight bytes will
be transmitted. If you use C0 in your RX or WX instruction, you will transmit the eight
bytes from C0 through C77.
In the example below, V40600 is the V-memory designation for the sixteen bits from
C0 through C17. Aliases are a convenient substitute for V-memory designations,
and can be used interchangeably in Read and Write instructions. VC0 is the alias for
V40600. Either nomenclature addresses the same 16 bits.
The alias is simply the name of the first bit in a group of sixteen bits, with V added as a
prefix. For example, VC0 represents the 16 bits beginning with C0. Word Memory,
Bit Memory and Aliases all use the octal numbering system.
C1 C2 C3 C4 C5 C6 C7 C10 C11 C12 C13 C14 C15 C16 C17 C0
Word Memory Address V40600
= VC0 (Alias)
V40601 = VC20
V40602 = VC40
V40603 = VC60
C74 C73 C72 C71 C70 C67 C66 C65 C64 C63 C62 C61 C60 C75 C76 C77
C57 C56 C55 C54 C53 C52 C51 C50 C47 C46 C45 C44 C43 C42 C41 C40
C37 C36 C35 C34 C33 C32 C31 C30 C27 C26 C25 C24 C23 C22 C21 C20
LDA
O40600
LD
K8
LD
K114
WX
LDA
O40600
LD
K8
LD
K114
WX
VC100
LDA
O40600
LD
K8
LD
K114
WX
C100
The following Write routines are all equivalent. DirectSOFT32 gives you the
flexibility to identify the responding PLC’s memory area in three different ways, as
shown below.
V40605
Bit Memory
Word Memory
and Aliases