Hitachi L2002 Output Deviation for PID Control

4–42

Using Intelligent Output Terminals

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.

SP, PV				Process variable
					Setpoint
	C044
	C044
[OD]		1
			ON			ON
Signal		0

t

Operations and Monitoring

Option	Terminal	Function Name	Output			Description
Code	Symbol		State
04	OD	Output Deviation for	ON	when PID error is more than the set threshold for
		PID Control		the deviation signal
			OFF	when PID error is less than the set threshold for
				the deviation signal
Valid for outputs:		11, 12, AL0 – AL2		Example (requires output configuration—
				see page 3–54):
Required settings:		C044
					Inverter output				OD
Notes:
					terminal circuit
• The default difference value is set to 3%. To change
this value, change parameter C044 (deviation
							CM2	12		11
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
	–	RY
damaging the inverter’s output transistor.

Example for terminals [AL0], [AL1], [AL2] (requires output configuration—

see pages 4–36 and 3–54):

Inverter logic	OD
circuit board

		AL0	AL1		AL2
	Power
See I/O specs				Load
	supply
on page 4–6.