Interruption Due to System Error
Bit 3: AT_ERR_PWF_OR_EFB_FAIL
Auto-tuning is aborted if a system PLC event arises, thus preventing the sequence from unfolding completely. For example, a power outage will automatically stop the auto-tuning function, upon power restoration.
Bit 4: AT_ERR_SATUR
If the process value leaves the interval of the full scale (PV_INF, PV_SUP), autotuning is aborted and the loop controller reverts to its previous mode. Predicting the future process value even allows the autotuning to be stopped before the overflow occurs (when a first model has been identified).
Bit 5: AT_DV_TOO_SMALL
The amplitude of the step function is too brief to cause a significant process reaction. Therefore it is possible to increase AT_STEP.
Bit 7: AT_INCONSIST_RESP
The process response is inconsistent (gains are not both + or - ). This may be due to a significant disruption, coupling with other loops, etc. Auto-tuning is stopped and a diagnostic is generated.
Bit 10: AT_NOISE_TOO_HIGH
The process reaction to the step function is not large enough in relation to noise. Filter the process value or increase AT_STEP.
Step Duration (AT_TMAX) Too Short
Bit 9: AT_TMAX_TOO_SMALL
The response is not stabilized until the initial command returns. The calculated parameters are therefore false.
Process Value Initially Not Stabilized
Bit 8: AT_NOT_STAB_INIT
Auto-tuning was launched when the process value was not stabilized. If the process value deviation is significant in relation to the division, the test results will be false.
Step Duration (AT_TMAX) Too Long
Bit 11: AT_TMAX_TOO_HIGH
AT_TMAX determines the sampling frequency of process values used to calculate coefficients. AT_TMAX must be between 1 and 5 times the process ascent time.
Bit 12: AT_OVERSHOOT
This bit is positioned in state 1 if the reaction to a command division prompts an excessive process value overshoot (greater than 10%). Process does not match the models treated by the algorithm.
Bit 13: AT_UNDERSHOOT
This bit is positioned in state 1 if the reaction to a command scale prompts a response inversion in its initial phase (undershoot greater than 10%). Process does not match the models treated by the algorithm.
Bit 14: AT_UNSYMETRICAL_PT
The process is asymmetrical (not symmetrical).
Bit 15: AT_INTEGRATING_PT
Either it is an integrating process or AT_TMAX is too small and the process is asymmetrical. The calculated coefficients match the integrating process. If this is not the case, restart auto-tuning after increasing AT_TMAX.
