Mitsubishi Electric MELSEC FX3U - Character Strings; Character String Constant (ABC); Character String Data

163
FX3G/ FX 3U /FX 3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
5 How to Specify Devices and Constants to Instructions
5.3 Character Strings
1
Introduction
2
Overview
3
Instruction List
4
Devices in Detail
5
Specified the Device & Constant
6
Before Programming
7
Basic Instruction
8
FNC00-FNC09 Program Flow
9
FNC10-FNC19 Move & Compare
10
FNC20-FNC29 Arith. & Logic Operation
5.3 Character Strings
Character strings are classified into character string constants which directly specify character strings in
operands in applied instructions and character string data.
5.3.1 Character string constant ("ABC")
A device "character string" directly specifies a character string in a sequence program.
Put half-width characters inside quotation marks (example: "ABCD1234") in specification.
JIS8 code is available.
Up to 32 characters can be specified as a character string.
5.3.2 Character string data
With regard to character string data, a specified device to the NUL code (00H) is handled as one character
string in 1-byte units.
When expressing (recognizing) character string data by bit devices with digit specification, however, 16 bits
are required for data including the NUL code (00H) specifying the end of the character string data because
the instruction length is 16 bits. (Refer to Example 2 in the step 2 below.)
In the following cases, an operation error occurs in the applied instruction (error code: K6706):
• When "00H" is not specified in the corresponding device range after the source device number specified in
an applied instruction
• When there are insufficient devices for storing character string data (including "00H" or "0000H" indicating
the end of the character string data) in the destination devices specified in an applied instruction
1) Character string data stored in word devices
• Example of data which can be • Example of data which cannot be
recognized as character string data recognized as character string data
2) Character string data stored in bit devices with digit specification
• Example of data which can be • Examples of data which cannot be
recognized as character string data recognized as character string data
2nd character
4th character
6th character
00H
1st character
3rd character
5th character
21st character
"00H" indicating the end of
the character string can be
detected.
b15 b8 b7 b0
D100
D101
D102
D110
2nd character
4th character
6th character
"n"th character
1st character
3rd character
5th character
"(n-1)"th character
"00H" indicating the end of character string
cannot be detected from the specified
device to the end device number.
b15 b8 b7 b0
D100
D101
D102
D7999
… …
2nd character
4th character
6th character
00H
1st character
3rd character
5th character
13th character
"00H" indicating the
end of the character
string can be
detected.
16 bits
M115 to M100
M131 to M116
M147 to M132
M211 to M196
2nd character
4th character
6th character
"n"th character
1st character
3rd character
5th character
"(n-1)"th character
"00H" indicating the end of character string
cannot be detected from the specified
device to the end device number.
<Example 1>
16 bits
M115 to M100
M131 to M116
M147 to M132
M7679 to
M7664
2nd character
4th character
6th character
8th character
1st character
3rd character
5th character
00H
Because the data "00H" indicating the end
of the character string does not reach 16
bits, the end of the character string cannot
be recognized.
<Example 2>
16 bits
M7623 to M7608
M7639 to M7624
M7655 to M7640
M7671 to M7656
M7679 to M7672
7th character
…
…