5 program security, 6 auto tune – ABUS Technologies A9696 Series Universal Controller User Manual
Page 19
ABUS TECHNOLOGIES INC.
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A9696
7.4.8 FUNCTION KEY AND DIGITAL INPUT (I/O6) FUNCTIONS
Both the
F
key and the I/O6 digital input can be programmed to execute functions 7, 8, 9 and
10 shown in Table . The key function is configured in parameter “fFvn”. The digital input function is
configured in parameter IO6. The digital input can also be configured for function 6: Auto/Manual mode
change.
7.5 Program Security
Each menu cycle can be locked (protected) by pressing
and
simultaneously for 3
seconds. Press
and
for 3 seconds to unlock. A short blink of the display confirms the lock/unlock
change. This will alternately lock or unlock the
and
keys to avoid tampering.
For further protection, the unlock operation through the keypad may be disabled by changing
the position of an internal strap inside the controller:
When PROT is OFF, the user is allowed to lock and unlock the cycles using the keypad as
explained above. If PROT is ON, the cycles lock/unlock operation is disable.
7.6 Auto Tune
During auto tune the process is controlled in ON/OFF mode at the programmed Set-Point Value
(SV). Depending on the process characteristics large oscillations above and below SV may occur and
auto tuning may take several minutes to be concluded. The recommended procedure is as follows:
Disable the control output at the rvn prompt by selecting NO.
Select auto mode operation at the Avto prompt by selecting YES.
Disable the ramp and soak function (select NO) and program a new SV value other than the
present PV (close to the desired set point).
Enable auto tuning at the Atvn prompt by selecting YES.
Enable the control output at the rvn prompt by selecting YES.
During the auto tune procedure the soft-start function will not operate and large oscillations will
be induced around the setpoint. Make sure the process can accept these oscillations and fast control
output changes. If auto tuning results are not satisfactory refer to the table below for manual fine tuning
procedure.
Suggestions for manual tuning of PID parameters
PARAMETER
RESPONSE
SOLUTION
Proportional Band
Slow Response
Decrease
Large Oscillation
Increase
Integral Rate
Slow Response
Increase
Large Oscillation
Decrease
Derivative Time
Slow Response or
Instability
Decrease
Large Oscillation
Increase