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MELSEC-Q/QnA
7. HOW TO READ EXPLANATIONS FOR INSTRUCTIONS
MELSEC-Q/QnA
8. INCOMPLETE DERIVATIVE PID CONTROL INSTRUCTIONS
AND PROGRAM EXAMPLES
(6) For
S
, designate the first number of the device numbers that are designated in the I/O
data area. If file registers (R) are designated for the I/O data area, do not set memory
protect ON for the file registers (R).
If memory protect is set ON, correct PID operation will be precluded, although no error
will occur.
See Section 5.2 for details on the I/O data area.
(7) Execute the S.PIDCONT instruction in every scan even while the manual manipulated
value (MVMAN) is being output in the manual control mode.
The bumpless switching cannot be executed if the S.PIDCONT instruction has not been
executed.
See Section 4.3.1 for details on the bumpless switching.
(8) Use the READY signal to establish an interlock with respect to the individual modules,
so that the S.PIDCONT instruction is executed only when both the A/D converter
module for reading the PV (process value) and the D/A converter module for outputting
the MV (manipulated value) are normal.*
S.PIDCONT
D100
Control command
READY signal for the
A/D converter module
READY signal for the
D/A converter module
If the S.PIDCONT instruction is executed while either or both of the modules are faulty,
PID operation cannot be executed correctly because the PV (process value) cannot be
read correctly and/or the MV (manipulated value) cannot be output correctly.
[OPERATION ERRORS]
(1) An operation error will occur, the error flag (SM0) will be turned ON, and an error code
will be stored in SD0, in the following cases.
• When the S.PIDINIT instruction is executed before executing the S.PIDCONT
instruction.
(Error code: 4103)
• When the value set as the PID control data is outside the allowable range.
(Error code: 4100)
• When the device range allocated to the PID control data area, designated with
S
,
exceeds the last device number of the corresponding device.
(Error code: 4101)
REMARK
*: For details on the READY signals of the A/D converter module and D/A converter module,
refer to the manual for the relevant module.
8 - 4
(3) Indicates the expressions and instruction execution conditions in the ladder
mode.
Execution Condition
Executed while ON
Executed once at OFF ON
Symbol used on the
explanation page
(4) Explains the set data for each instruction and indicates the data type.
Data Type
Description
16-bit binary
Indicates that binary 16-bit data or the first number of a word device can be used.
(5) Indicates the function of the instruction.
(6) This shows a CPU module to which instructions are given.
: Usable, : Usable on condition, : Unusable
(7) Indicates the conditions that will cause errors and the error numbers.
(7)
Содержание Q Mode
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Страница 18: ...1 4 MELSEC Q QnA 1 GENERAL DESCRIPTION MEMO ...
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Страница 74: ...6 2 MELSEC Q QnA 6 PID CONTROL INSTRUCTIONS MEMO ...
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