Output Deviation For Pid Control - Hitachi L300P Series Instruction Manual

4–40
Using Intelligent Output Terminals
Output Deviation
for PID Control
The PID loop error is defined as the
magnitude (absolute value) of the differ-
ence between the Setpoint (target value)
and the Process Variable (actual value).
When the error magnitude exceeds the
preset value for C044, the [OD] terminal
signal turns ON. Refer to "PID Loop
Operation" on page 4–58.
Opt.
Symbol Function Name
Code
04 OD Output deviation
for PID control
11, 12, AL0 – AL2
Valid for
outputs:
C044
Required
settings:
Notes:
• The default deviation value is set to 3%. To
change this value, change parameter C044
(deviation level).
NOTE: The example circuit in the table above drives a relay coil. Note the use of a diode to
prevent the negative-going turn-off spike generated by the coil from damaging the inverter's
output transistor.
Error
(SP-PV)
C044
Set
value
C044
[OD]
Signal
Output
Description
State
ON when PID error is more than the set
threshold for the deviation signal
OFF when PID error is less than the set thresh-
old for the deviation signal
Example: (Requires output configuration—
see page 3–48.)
Inverter output terminal circuit
12C 12A
24VDC
See I/O specs on page 4–8.
Process variable
Setpoint
t
OD
11C 11A
+
L
–