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3-1 How does Memory Link work
3-1-1 PT memory
With Memory Link you assign objects word and bit to PT memory. PT memory is an
imaginary PLC area inside the NS. NS performs read/write operations to internal PT
memory. Host reads/writes PT memory as required and so controls and monitors NS.
PT memory consists of 2 territories: Bit ($B) and Word ($W).
PT memory can be also used to store functional object display character strings or as
data area for the macro function.
3-1-2 Command and response
With Memory Link, the following commands enable data transmission between host
and PT.
- Read-out command / response
This is the command for reading out PT memory of PT.
When host gives command, PT responds the contents of the designated data.
There are 2 commands that vary with the type of PT memory.
Command
Title
Action
RM
Read out PT ($W) memory
Read out $W data in PT memory
RB
Read out PT ($B) memory
Read out $B data in PT memory
- Write command/response
This is the command to write designated data to PT memory area in PT.
Host gives command. PT responds whether or not the writing was completed
successfully.
The successful completion response may be omitted by particular setting the
Response parameter in the communications conditions menu.
The following 4 commands can be given:
Command
Title
Action
WM
Write to PT memory ($W)
Write data to PT memory $W
WB
Write to PT memory ($B)
Write data to PT memory $B
FM
FILL PT memory ($W)
Write designated data to multiple
PT memory $W
FB
FILL PT memory ($B)
Write designated data (0 or 1) to
Multiple PT memory $B.
- Notify Command
