Output Deviation For Pid Control - Hitachi CONVENTION 14 Instruction Manual

Output Deviation for PID Control

The PID loop error is defined as the
magnitude (absolute value) of the difference
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–
56.
Option Terminal
Code Symbol
04 OD Output Deviation for
PID Control
Valid for inputs: 11, AL0 – AL2
Required settings C044
Notes:
The default difference value is set to 3%. To
change this value, change parameter C044
(deviation level).
The example circuit for terminal [11] 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.
Function Name State
ON
OFF
SP,PV
C044
C044
[OD] 1
ON
signal
0
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 for terminal [11] (default output
configuration shown – see
Inverter output
terminal circuit
CM2
Example for terminal [AL0], [AL1], [AL2] (requires
output configuration – see
Inverter logic
circuit board
AL0 AL1
Power
supply
See I/O specs on page 4-6
4 − 43
4 43
Process variable
Setpoint
ON
page 3-54):
OD
11
RY
page 4-35 and 3-54):
OD
AL2
Load
t