Omron Sysmac CJ Series, Operation Manual

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Selecting PID Control or ON/OFF Control Section 3-5
3-5 Selecting PID Control or ON/OFF Control
A switch on the front of the Unit (pin 6 of the DIP switch) selects whether the
Temperature Control Unit uses ON/OFF control or PID control with 2 degrees
of freedom.
The control method setting applies to all of the Unit’s control loops. It is not
possible to set different control method settings for the control loops.
If the control method setting is changed during operation, the new setting will
not become effective until the power is turned OFF and ON again.
The factory setting is OFF (PID control), as shown in the diagram above.
3-5-1 Setting the Control Method (Pin 6)
PID Control with Two
Degrees of Freedom With PID control, it is necessary to set the proportional band (P), integral time
(I), and derivative time (D). These settings can be made automatically with
autotuning or manually. Refer to
3-9 Setting the PID Constants for more
details on the PID constants.
ON/OFF Control With ON/OFF control, the control output will be ON when the PV is below the
SV. The control output will be OFF when the PV is at or above the SV. (This is
the operation when the Unit is set for reverse operation. This operation will
work in the opposite way for forward operation.)
3-6 Setting the Control Period
• This setting determines the output period (control period) for PID control.
System control will improve with a shorter control period, but if you are
using relays for heater control, we recommend setting a control period of
at least 20 s to increase the relay’s lifetime. If necessary, the control
period can be adjusted during trial operation.
• Set the control period in the corresponding word of the Operating Param-
eters in the DM words allocated to the Unit. (See the following table.) A
standard setting is 2 s, but the default setting is 20 s.
• Each control loop has a separate control period setting.
3-6-1 Control Period Settings
Setting the Loop 1
Control Period to 2 s
To set the control period for loop 1 to 2 s, set word DM (m+13) to 0002. The
control periods are set in seconds and the default setting is 20 s.
123
4
5678
Pin 6
Control method
PID control
ON/OFF control
Setting
OFF
ON
DM word Setting Setting ranges
BCD Binary
D (m+13) Loop 1 control period 0001 to 0099 0001 to 0063
D (m+23) Loop 2 control period 0001 to 0099 0001 to 0063
D (m+53) Loop 3 control period 0001 to 0099 0001 to 0063
D (m+63) Loop 4 control period 0001 to 0099 0001 to 0063