Output Deviation For Pid Control - Hitachi L2002 Instruction Manual

4–42
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
Operation" on page
Option Terminal
Code Symbol
04 OD
Valid for outputs:
Required settings:
Notes:
•
The default difference value is set to 3%. To change
this value, change parameter C044 (deviation
level).
•
The example circuit for terminal [12] 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.
"PID Loop
4–56.
Output
Function Name
State
Output Deviation for ON
PID Control
OFF
11, 12, AL0 – AL2
C044
SP, PV
C044
C044
[OD] 1
ON
0
Signal
Description
when PID error is more than the set threshold for
the deviation signal
when PID error is less than the set threshold for
the deviation signal
Example (requires output configuration—
see page 3–54):
Inverter output
terminal circuit
Example for terminals [AL0], [AL1], [AL2]
(requires output configuration—
4–36
see pages and 3–54):
Inverter logic
circuit board
AL0
Power
See I/O specs
supply
on page 4–6.
Process variable
Setpoint
ON
t
OD
CM2 12 11
+
RY
–
OD
AL1 AL2
Load