406
Network Instructions
Section 5-29
When the execution condition first goes from OFF to ON, PID(––) reads the
parameters and initializes the work area. There is a built-in function to change
the output data continuously at startup because sudden changes in the output
data might adversely affect the controlled system.
!Caution
Changes made to the parameters will not be effective until the execution con-
dition for PID(––) goes from OFF to ON.
Note
Do not use PID(––) in the following situations; it may not be executed properly.
In interrupt programs
In subroutine programs
In interlocked program sections (between IL and ILC)
In jump program sections (between JMP and JME)
In step ladder program section (created with STEP)
When the execution condition is ON, PID(––) performs the PID calculation on
the input data when the sampling period has elapsed. The sampling period is
the time that must pass before input data is read for processing.
The following diagram shows the relationship between the sampling period
and PID processing. PID processing is performed only when the sampling
period (100 ms in this case) has elapsed.
Flags
ER:
There is an error in the parameter settings.
The cycle time is more than twice as long as the sampling period, so
PID(––) cannot be executed accurately. PID(––) will be executed in
this case.
Indirectly addressed EM/DM word is non-existent.
(Content of
*
EM/
*
DM word is not BCD, or the EM/DM area boundary
has been exceeded.)
CY:
ON when PID processing has been performed. (OFF when the sam-
pling period has not elapsed.)
5-29 Network Instructions
The network instructions are used for communicating with other PCs host
computers linked through the Controller Link System.
5-29-1 NETWORK SEND – SEND(90)
70 ms
1 cycle
60 ms
70 ms
70 ms
PID processing
with initial values
(0 ms)
No processing
(70 ms)
PID processing
(70+30=100 ms,
no carryover)
No processing
(60 ms)
PID processing
(130 ms, 30 ms carryover)
S
:
Source beginning word
IR, SR, AR, DM, EM, HR, TIM/CNT, LR
D
:
Destination beginning word
IR, SR, AR, DM, EM, HR, TIM/CNT, LR
Operand Data Areas
C
:
First control data word
IR, SR, AR, DM, EM, HR, TIM/CNT, LR
Ladder Symbols
SEND(90)
S
D
C
@SEND(90)
S
D
C
