Rockwell Automation 1746-BTM Barrel Temperature Control Module User Manual - Manual (Page 53)

Publication 1746-UM010B-EN-P - April 2001
Control and Autotune a Loop 5-7
Example: Autotune non–barrel control applications
1. Enter a safe non–barrel autotune disturbance size in the M1 file.
•
Disturbance size is the step output that the module uses to
autotune. For example, if disturbance size is 15% and current
CV is:
0% when autotune is invoked, the CV changes to 15%
10% when autotune is invoked, the CV changes to 25%
•
Optimum disturbance lets temperature rise, then level off. If
too large, temperature will not level off and autotune will be
unsuccessful.
2. Make sure all zones have valid M1 files and no parameter errors.
3. Start Autotune from a cold start or start from a steady–state
temperature.
•
If doing a cold start, invoke autotune after putting loop into
manual mode and setting manual CV output to zero.
•
If starting from a steady–state temperature, invoke autotune.
4. When autotune completes, upload the autotune and gains block.
5. Return the zone to auto mode.
Troubleshooting Autotune
The module reports successful completion of autotune in status word
N10: 168-171, bits 03, and 04 in the input image buffer table. If
autotune was not successful, look for autotune error codes in
N10:212-215. Refer to Locating Error Code Information on page 8-2.
Temperature
dead time
Temperature for safe autotune disturbance size
Autotune completes when
temperature reaches steady
state
Time