Execution Of Commands - LG MASTER-K 120S Series User Manual

Chapter 8 Communication Functions

8.1.6 Execution of commands

1) Individual reading of device(R(r)SS)
(1) Introduction
This is a function that reads PLC device specified in accord with memory data type. Separate device memory can be read
up to 16 at a time.
(2) PC request format
Format name Header
Ex. of frame ENQ
ASCII value H05
Item
BCC
Number of
Blocks
Device length
(Length of
device name)
Device name
Remark
'H' of example frame represents hex value, and is unnecessary during preparing real frame.
Station Command
Command
No. type
H20 R(r) SS
H3230 H52(72) H5353
When command is lowercase(r), only one lower byte of the value resulted by adding 1 Byte
each to ASCII values from ENQ to EOT is converted into ASCII and added to BCC. For
example, the BCC of the above frame is gotten as below:
H05+H32+H30+H72+H53+H53+H30+H31+H30+H36+H25+H4D+H57+H31+H30+H30+H04
=H03A4 Therefore BCC value is A4.
This specifies how much of the blocks composed of "[device length][device name]" are in this
request format. This can be set up to 16. Therefore, the value of [Number of blocks] must be
set between H01(ASCII value:3031)-H10(ASCII value:3030).
This indicates the number of name's characters that means device, which is allowable up to 16
characters. This value is one of ASCII converted from hex type, and the range is from
H01(ASCII value:3031) to H10(ASCII value:3130). For example, if the device name is %MW0,
it has 4 characters to be H04 as its length. If %MW000 characters to be H06.
Address to be actually read is entered. This must be ASCII value within 16 characters, and in
this name, digits, upper/lower case, '%' only is allowable to be entered.
Number Device
Device name
of blocks length
H01 H06 %MW100
H3031 H3036 H254D57313030
1 block(setting can be repeated up to max. 16 blocks)
Explanation
8-9
Frame
Tail
......
check
EOT BCC
H04