Rockwell Automation 1746-BTM Barrel Temperature Control Module User Manual - Manual (Page 37)

Publication 1746-UM010B-EN-P - April 2001
Configuring the Module 3-11
Configuration Block, M1
File, Loops 1-4 N10:0-100 Configuration block (M1 file) contains 101 words as listed below. Data
table location for Loops 1-4 are located in N10. For each additional
1746-BTM, add 1 to N10 (N11:0-100).
Startup Aggressiveness
factor The startup aggressiveness factor (SAF) modifies the pre-set point
value. The pre-set point value is the temperature at which you switch
from the cold startup algorithms to PID control. The pre-set point
value is calculated from the auto tune data. The value is returned
through the rotator bits. In the example code it would be found in
Nxx:236 thru 239, a value for each channel.
The startup aggressiveness factor increases the pre-set point value by
percentage. For example:
EXAMPLE
Consider:
•
setpoint is 400.0°
•
preset point for channel 1 (nxx:236) is 75°
•
startup aggressiveness factor is 0%
The point at which you would switch from the cold
startup algorithm to PID control would be:
If the startup SAF factor is set to 25%, the point at
which you would switch from the cold startup
algorithms to PID control would be:
IMPORTANT
The higher the startup aggressiveness factor is, the
closer to setpoint you will go before you switch from
the cold startup algorithms to PID control. If your
pre-set point is too close to the actual setpoint you
can expect overshoot to occur.
If you change the startup aggressiveness factor you
will need to redownload the M1 configuration and
the M0 autotune block for the change to take effect.
setpoint 1
SAF
100
-----------




presetpoint
Ч


–


–
400.00 1
0
( )
100
---------




75.0
Ч


–


325
°
= –
400.00 1
25
( )
100
----------




75.0
Ч


– 

343.8
°
= –