Automation Direct D0-DCM, Руководство пользователя

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Getting Started
User Application
Guidelines
RLL
Programming
for Communications
4–4
RLL Programming for Communications
DL05/06 Data Communications Module, 1st Edition, 08/05
The second Load (LD) instruction
determines the length of the data block to
be transmitted during the Read or Write
communication. This instruction will also
accept two data types. Use a “K” to
designate the number as a constant. Use a
“V” if you are entering the address of a
register.
For Word Memory data, you must use a
multiple of two bytes between 2 and 128.
For Bit Memory data, you can use any
multiple of one byte between 1 and 128.
For more information about addressing
Word and Bit Memory, see page 4-6.
LD
K8
LD
K114
PLC Memory
4 words = 8 bytes
LD
K8
LD
K114
LDA
O40600
The Load Address (LDA) instruction
specifies the V-memory address of the
beginning memory register in the master
PLC. The data block to be transmitted will
begin at this address and extend the
number of bytes specified in the preceding
LD instruction. The leading “O” indicates
this is an octal number. Simply substitute
the letter “O” for the “V” in the V-memory
designation. For example, V40600
becomes O40600.
Read instructions copy the data block from
the slave PLC memory into the master PLC
memory.
Write instructions copy the data block from
the master PLC memory into the slave PLC
memory.
V40600
V40601
V40602
V40603
V40577
V40604
Master PLC
The Second LD
Instruction
The LDA
Instruction