Hitachi L2002 - Manual (Page 186)

Using Intelligent Output Terminals
Oper
ations
and Monitor
ing
4–42
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 4–56 .
[OD]
Signal
SP, PV
1
0
t
ON ON
Setpoint
Process variable
C044
C044
Option
Code
Terminal
Symbol
Function Name
Output
State
Description
04 OD Output Deviation for
PID Control ON when PID error is more than the set threshold for
the deviation signal
OFF when PID error is less than the set threshold for
the deviation signal
Valid for outputs: 11, 12, 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 [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.
RY
+
–
Example (requires output configuration—
see page
3–54 ):
Inverter output
terminal circuit OD
Example for terminals [AL0], [AL1], [AL2]
(requires output configuration—
see pages
4–36 and 3–54 ):
AL0 AL2 AL1
Inverter logic
circuit board
See I/O specs
on page
4–6 .
OD
Load
Power
supply
12 11 CM2