LSIS XGL-EFMTB - Read Continuous Direct Variable

Chapter 8 Dedicated Communication
8-8
8.2.2 Read Continuous Direct Variable
(1) Introduction
This function is used to read the data of directly defined PLC device memory continuously as
many as specified from the address specified.
(2) Request format (PC ⇒ PLC)
■ Read Request of Continuous Variable (MMI  PLC)
Item
Size (byte)
Description
Instruction
2
h0054 : Read Request
Data type
2
h0014 : Continuous
Reserved area
2
h0000 : Don’t Care.
Number of blocks
2
It is fixed with h0001 for Continuous read.
Variable length
2
The number of characters in the variable field; Max. 16
Variable
Length
Variable name
Variable name; Byte type of direct variables only available
(In other words, types of %MB / %PB / %DB/… available:
supporting devices: P,N,L,K,T,C,D,N, F )
It displays block’s start address. (Ex. %MB0, %PB0)
Number of Data
2
Data Size in byte whose Maximum value is 1400.(h0578)
Format
name
Header Instruction
Data
type
Reserved
area
Number
of
blocks
Variable
length
Variable
Number
of data
Code
(Ex.)
... h0054 h0014 h0000 h0001 h0006 %MB000 h0006
Notes
(1) Number of data means the number of data in byte unit (up to 1,400 bytes available).
1) Data type
h0014 only can be used for the data type.
2) Number of blocks
Definitely h0001 only can be used for the number of blocks.
3) Variable length
It means the number of characters of the variable name which is available up to 16 characters,
whose range is h0001 ~ h0010.
4) Variable
It stands for variable’s address to read actually. It shall be ASCII value within 16 characters.
Others than figure, capital/small letter, ‘%’ and ’.’ are not allowed for the variable name.
Based on the PLC type, types of variables available to read continuously are as described
below.