RKC INSTRUMENT Z-TIO-G, Instruction Manual

Page: 185 / 246

9. COMMUNICATION DATA DESCRIPTION
IMS01T28-E4
9-77
AT differential gap time
RKC communication
identifier GH
Modbus
register address ch1: 0292H (658)
ch2: 0293H (659)
Use to set an ON/OFF action differential gap time for Autotuning. This function prevents the AT function
from malfunctioning caused by noise.
Attribute:
R/W
Digits:
7 digits
Number of data:
2 (Data of each channel)
Data range:
0.0 to 50.0 seconds
Factory set value:
10.0
Related parameters:
PID/AT transfer (P. 9-13)
Function:
In order to prevent the output from chattering due to the fluctuation of a Measured
value (PV) caused by noise during Autotuning, the output on or off state is held
until “AT differential gap time” has passed after the output on/off state is changed
to the other.
Set “AT differential gap time” to “1/100

Time required for temperature rise.”
[Example]
A: AT cycle time when the AT differential gap time is set to 0.0 second
The output chatters due to the fluctuation of the Measured value (PV) caused
by noise, and Autotuning function is not able to monitor appropriate cycles to
compute suitable PID values.
B: AT cycle time when the AT differential gap time is set to “Time corresponding
to 0.25 cycles.” The fluctuation of a Measured value (PV) caused by noise is
ignored and as a result Autotuning function is able to monitor appropriate
cycles to compute suitable PID values.
Measured value (PV)
Set value (SV) 
Time

AT start
A
Fluctuation of Measured value (PV)
caused by noise

AT differential gap time
B
The factory set value of the AT cycle is 2 cycles.