Instruction Manual

Tuning

SELF TUNE MESSAGES AND TROUBLESHOOTING

Refer to Chapter 7 for more information on the Self Tune function of the 535 controller.

When the Pretune function terminates, one of the following messages will appear:

Message

A

Pretune

Type

Conclusion/Problem

A

Corrective Action

A

COMPLETED

ABORTED

LIMIT ERR.

TIME OUT

NOISE ERR.

INPUT ERR.

OUT. ERROR

DATA ERR.

ZERO ERR.

DEV. ERROR

RETRY

1

2, 3

1, 2, 3

1

2, 3

1, 2, 3

1, 2, 3

1, 2, 3

1, 2, 3

1, 2, 3

1, 2, 3

1, 2, 3

1, 2, 3

2,3

2,3

1

1, 2, 3

PRETUNE has generated initial PID and the Dead Time values.

PRETUNE has generated initial PID, Response Time,

Noise Band and the Dead Time values.

User has aborted PRETUNE before completion.

The Process Variable went beyond the HI LIMIT or LOW

LIMIT.

The Process Variable went beyond the HI LIMIT or LOW

LIMIT.

The initial Process Variable was near or beyond the HI

LIMIT or LOW LIMIT.

TIMEOUT limit was reached before PRETUNE completed.

Too much PV noise was detected.

PV or Cold Junction break detected during PRETUNE.

Change the HI LIMIT and LOW LIMIT, or the HIGH OUT and LOW OUT, and run PRETUNE again.

Change the HI LIMIT and LOW LIMIT, or the OUT.STEP

size, and run PRETUNE again.

Change the manual output percentage, or the HI LIMIT and

LOW LIMIT, and run PRETUNE again.

Set a longer TIMEOUT period and/or increase the

OUT.STEP size, and run PRETUNE again.

Eliminate the noise source (if possible) or increase the

OUT.STEP and run PRETUNE again.

Check the described conditions and make corrections or repairs.

PV HIGH or PV LOW detected during PRETUNE.

SLIDEWIRE break detected during PRETUNE.

REMOTE SP break detected during PRETUNE.

The initial control output is outside the high and low limits defined in the Control Menu.

The PV moved too quickly to be Analyzed.

One or more model parameters are calculated to be zero.

The initial PV is too close to the TUNE PT.

The Process Variable went beyond the HI LIMIT or LOW

LIMIT

Change the manual output percent and run PRETUNE again.

Increase the OUT.STEP size and run PRETUNE again.

Increase the OUT.STEP size and run PRETUNE again.

Move Tune PT. (or the set point if TUNE PT. is automatic) farther from the process variable and run PRETUNE again.

Check if any PID values are generated and if they are acceptable. If not, eliminate noise sources (if possible) and run PRETUNE again.

If Pretune and Adaptive Tune do not generate optimal PID values for control, check the following menu entries:

Message

A

RESPONSE

TIME

NOISE BAND

Potential Problem

A

Adaptive Tune cannot run if RESPONSE TIME is inaccurate

Adaptive Tune cannot compensate for PV oscillation due to hysteresis of output device (e.g., a sticky valve).

PRETUNE Pretune does not develop optimum PID parameters.

Corrective Action

A

Run TYPE 2 or TYPE 3 Pretune to obtain the correct value, or enter it manually.

Set NOISE BAND large enough to prevent Adaptive Tune from acting on the oscillation. If oscillation is not acceptable, consider replacing valve.

Wrong Pretune TYPE selected. Refer to Chapter 7, the

Section on Self Tune.

70 Chapter 6 535 User's Manual