West Control Solutions CALogix - Manual (Page 18)

Cycle time recommendations
− It is recommended that relay outputs should not have a cycle time of less than 10S. If a cycle time of less than 10s
is required, solid state drive outputs are advised.
SECOND AND THIRD SETPOINTS (SP2 and SP3)
Primary Alarm Modes
− Configure SP2 and SP3 outputs to operate as an alarm from setpoint 2 and 3 control sections in the ‘module
settings menu’
The alarms will be individually triggered when the process value changes according to the options listed
below.
DVHI
Rises above the main setpoint by the value inserted at setpoint 2 or 3
DVLO Falls below the main setpoint by the value inserted at setpoint 2 or 3
Band Rises above or falls below the main setpoint by the value inserted at setpoint 2 or 3
FSHI Rises above the full scale setting of setpoint 2 or 3
FSLO Falls below the full scale setting of setpoint 2 or 3
COOL Heat-cool operation, see section on heat-cool
EOP Event Output (See Programmer section)
Subsidiary SP2 / SP3 modes
− The following additional subsidiary alarm functions can be added to any primary alarm configurations.
−
Latch Once activated, the alarms will latch and can be manually reset via CALogix-sw or an operator panel
when the alarm condition has been removed.
Hold This feature inhibits alarm operations on power-up and is automatically disabled
once the process reaches the alarm setting.
Lt.ho Combines the effects of both Latch and Hold and can be applied to any primary
alarm configuration
If you configure SP2 or SP3 as an alarm in on.off mode please be aware the output and LED indicator to the alarm will be
energised when the alarm is not active and de-energised when alarm is active. By setting display alarm (setpoint 2 and 3
settings) to on the alarm display indicator (bell) will replace the output LED in CALogix-sw when an alarm condition exists.
Note :
Changing SP2 or 3 operating mode will default the setpoint back to zero when applied to the base-unit, this will not
be updated in the property sheet until closed and read back.
HEAT-COOL
Heat-cool strategy is a feature that improves control of processes that need heating and cooling, for example:
− Environmental test chambers used in rooms where ambient temperature can vary above and below test
temperature.
− Plastics extruders where the material initially needs heating, then cooling, when it begins to heat itself
exothermically due to pressure and friction applied by the process.
The purpose of cool strategy is to maintain accurate control of the process with a smooth transition between heating to
cooling. This is achieved by using PID control for both heating and cooling with the proportioning bands linked by an
adjustable deadband.
Tuning CALogix for heat-cool
Enter a setpoint then allow the process to reach the setpoint using factory settings for heating only. Ensure that procedure
for initial settings has been carried out before heating the application.
When application process value has stabilised at setpoint change the following parameters
Parameter
Menu Value
DAC Setpoint 1 control 1
Cycle time Setpoint 1 control 10
Operating mode Setpoint 2 control COOL
Cycle time Setpoint 2 control 10
Use cycle time Autotune settings No
Apply these settings then set
Mode
Autotune settings ATSP
When the setting is applied there will be a temporary disturbance in temperature as autotune is running.
‘ATSP’ is displayed on the module within CALogix-sw controller image. Once ‘ATSP’ is no longer displayed the controller is
tuned.
Further settings
If regular oscillations occur change Use cycle time to Yes. See section on proportional cycle time.
Note :
minimum recommended cycle time using relay outputs is 10s.
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