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When any of D.O1, D.O2 or D.O1.2 is selected for EIFN, the output 1 and/or output
2 will revert to their normal conditions as soon as the event input is released.
LOCK: All parameters are locked to prevent from being changed.
SP2F Function: Define format of SP2 value. If SP2F in the setup menu is selected
with ACTU, the event input function will use SP2 value for its second set point. If
SP2F is selected with DEVI, the SP1 value will be added to SP2. The sum of SP1
and SP2 (SP1+SP2) will be used by the event input function for the second set
point value. In certain applications it is desirable to move second set point value
with respect to set point 1 value. The DEVI function for SP2 provides a convenient
way in this case.
4.3.1.1.4.16 Second Set Point
In certain applications it is desirable to change the set point automatically without the need to
adjust the set point. You can apply a signal to event input terminals. The signal applied to event
input may come from a Timer, a PLC, and an Alarm Relay, a Manual switch or other devices.
Select SP2 for EIFN which is contained in setup menu. This is available only with the case that
SP1.2, MIN.R or HR.R is used for SPMD, where MIN.R and HR.R are used for the ramping
function.
Application 1: A process is required to be heated at a higher temperature as soon as its
pressure exceeds a certain limit. Set SPMD=SP1.2, EIFN=SP2 (or SP .P2 if the second PID is
required for the higher temperature too).The pressure gauge is switched ON as it senses a higher
pressure. Connect the output contacts of the pressure gauge to the event input. SP1 is set with a
normal temperature and SP2 is set with a higher temperature. Choose ACTU for SP2F.
Application 2: An oven is required to be heated at 300°C from 8.00 AM to 6.00 PM After 6.00
PM it is desirable to be maintained at 80°C. Use a programmable 24 hours cycle timer for this
purpose. The timer output is used to control event input. Set SPMD=SP1.2, and EIFN=SP2 (or
SP .P2 if the second PID is required to be used for the second set point).SP1 is set with 300°C and
SP2 is set with 80°C. Choose ACTU for SP2F. After 6.00 PM the timer output is closed. The event
input function will select SP2 (=80°C) to control the process.
4.3.1.1.4.17 Second PID Set
In certain applications the process characteristics is strongly related to its process value. The
Process Control Card provides two set of PID values. When the process is changed to different set
point, the PID values can be switched to another set to achieve an optimum condition.
The optimal PID values for a process may vary with its process value and set point. Hence if a
process is used for a wide range of set point, dual PID values are necessary to optimize the control
performance. If the first PID set is selected (event input is not applied) during auto-tuning
procedure, the PID values will be stored in PB1, TI1 and TD1. Similarly, if the second PID set is
selected (event input is applied while PID2 or SP.P2 is selected for EIFN) during auto-tuning, the
PID values will be stored in PB2, TI2 and TD2 as soon as auto-tuning is completed.
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