ISPSoft User Manual

Chapter 11 Structured Text
However, if the data type of one operand is INT and the data type of the other operand is WORD,
the operands can take part in the operation. Likewise, if the data type of one operand is DINT and
the data type of the other operand is DWORD, the operands can take part in the operation. If the
data lengths of the operands in an expression are different, the operands can not take part in the
operation.
• If the data type of a symbol is WORD, DWORD, LWORD, INT, DINT, or LINT, the system regards
it as a signed integer during the operation.
• Although there is no limit on the number of lines, users still have to consider the capacity of the
memory in the PLC.
• The sections of a structured text in ISPSoft can be copied/cut/pasted. Users can copy the text in a
file edited with a text editor into a structured text in ISPSoft.
• The instructions that a structured text supports are as follows.
DVP series PLC
AH500 series CPU module
All the basic instructions are not supported. For example, LD, LDI, OUT, SET, RST, LD&, and
etc are not supported.
All the pulse instructions are not supported. For example, ROLP, RORP, BCDP, TRDP, and etc
are not supported.
PLS, PLF, FOR, NEXT, CJ, MC, MCR, STL,
RET, and etc are not supported.
11.2 Structure of a Statement
11.2.1 Assignment Structure─:=
• Format
The Four Arithmetic Operations instructions,
the Logical Operation instructions, the
Contact Type Logic Operation instructions,
and the Structure Creation instructions are not
supported. PLS, PLF, MOV, DMOV, DFMOV,
$MOV, MC, MCR, CJ, JMP, GOEND, and etc
are not supported.
• Description
The value represented by the expression at the right side of := is assigned to the device or the
symbol at the left side of :=.
• Rules and limits
‣ The expression at the right side of := can be a constant, a device, a symbol, or an arithmetic
expression. Only a device or a symbol can be at the left side of :=.
‣ The operands at both sides of := must conform to the rules listed below.
(a) One operand is an M/S/T/C/HC device, and the other operand is a symbol whose data
type is BOOL/STEP/TIMER/COUNTER. (The device assigned to the operand which is a
symbol is a bit device.)
(b) One operand is a D/L device, and the other operand is a symbol whose data type is not
BOOL/STEP/REAL/STRING.
(c) One operand is a T/C device, and the other operand is a D/L device or a symbol whose
data type is WORD/INT/TIMER/COUNTER.
(d) One operand is a D/L/HC device, or a symbol whose data type is COUNTER, and to which
a HC device is assigned. The other operand is a symbol whose data type is
DWORD/DINT.
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