Adjustment Mode Parameter "Ctrl - Inkbird ITC-100 User Manual

current output). Output current are 0-10mA and 2-40mA.
When oPI=2, output mode is time proportioning output, and AL1 act as
output synchronizing with main output. Under this mode, the AL1 of the
instrument can't be used to output alarm signals as it's used as output.
Only AL2 is available for alarm signals (refer to 6.8).
oPL and oPH are the output low limit and high limit. Attentions: the setting
of oPI should be in accordance with the module of main output.
When oPI=1 (current output), oPL and oPH are as following:
0-10mA output: oPL=0, oPH=100
4-20mA output: oPL=40, oPH=200
Example for nonstandard output current: 2-8mA output: oPL=20, oPH=80. 100%. It's definition is as following.
oPI=0,2 (time proportioning output). Time proportioning output controls
the ratio of open and close of relay (or ratio of high and low voltage
output of SSR) in a fixed period to realize output variation. Time
proportioning output could be regarded as a square wave, its period
is equal to control period Ctl. Output value is proportional to the duty
ratio of square wave, varying from 0% to 100%. Users can use oPL
and oPH to limit the output range of time proportioning output. For
example, to limit the output within range 20%-60%, set oPL=20,
oPH=60. Generally, the default setting of time proportioning output is
oPL=0, oPH=100, that is, no output limitation.
(wave when output is 40% and 60%)
Figure 7 diagram of time proportioning output

6.10.2 Adjustment mode parameter "CtrL"

ITC-100 allows digital adjustment or professional PID adjustment.
Select it by CtrL parameter.
When CtrL=0, adopt digital adjustment (ON-OFF). It's only for
applications where the requirements are not strict.
When CtrL=1, adopt professional PID adjustment. It's an improvement
based on PID adjustment and fuzzy adjustment, suitable for various
objects, and well control on fast changing objects and hysteresis. It's
the default setting when product leaving factory. Under this setting,
self-tuning could be launched by panel operation.
When CtrL=2, launch self-tuning. It's same operation as launching
self-tuning by panel operation. If another self-tuning is needed after
self-tuning, set CtrL as 2 to re-launch self-tuning.
When CtrL=3, adopt professional PID adjustment. After self-tuning,
the instrument will apply such setting. Under this setting, no self-tuning
is allowed from panel operation, thus to avoid maloperation to launch
self-tuning.
6.11 PID control parameters related to self-tuning "M50, P, t" and
functional parameter "CtL"
PID control parameters M50, P and t are the control parameters for
professional PID adjusting algorithm. M50, P, and t are determined by
self-tuning. This instrument adopted the latest professional PID
adjustment which is a new algorithm enhanced with fuzzy logic.
Following are the definition of each parameter.
6.11.1 Holding parameter "M50"
M50 defines the deviation for measured value when the object is stable,
and the output value is 50% (when oPI=1, the current is 5.0mA). For
example, for finding the best M50 value of a electric furnace, assume
the output is keeping at 50%, the temperature of the electric furnace in
stable stage is 700℃, while when the output is 0%, the temperature of
electric furnace is room temperature 25℃, then M50 (optimal value) is
700-25=675℃.
M50 is mainly for adjusting the integral action of adjusting algorithm. The
smaller the M50, the strong the integral action. The larger the M50, the
weak the integral action (integral time will increase). But when M50=0,
system will cancel integral action.
6.11.2 Rate parameter "P"
P is inversely proportional to the measurement variation when the output is
P= 100÷increased measuring value per second, the unit is ℃ or 10
defined units (when linear input). For example, when the output is 100%,
no heat dissipation, and the temperature of the electric furnace increases
1℃ per second, then:
P=100÷1=100
P has influence to adjusting proportion and differential. When the P value
increased, the adjusting proportion and differential action will increase
proportionally; while when the P value decreased, the adjusting proportion
and differential action will decrease proportionally. P has no influence to
integral action. Set P=0 is equal to set P=0.5.
6.11.3 Hysteresis time "t"
For industrial control, the hysteresis effect of object system is the main factor
which influences control effect. The larger the system hysteresis time, more
difficult to achieve ideal control effect. Hysteresis time t is a new important
parameter introduced into professional PID algorithm in comparing with PID
algorithm. The instrument can conduct fuzzy logic operation according to
parameter t to perfectly solve overshoot and oscillation, as well as achieve
fastest respond speed. t is defined as the time needed for the electric furnace
reaching 63.5% of its maximum heating rate when heating with a fixed power.
6.11.4 Function parameter "CtL"
CtL value can be set between 0.5-120 seconds (CtL value 0 is equal to 0.5
seconds). It reflects the operation speed of instrument control. For time
proportioning output (triggering by SSR voltage/relay/control silicon), it
represents the control period of the instrument; for linear current output,
it controls the output fluctuation (time constant for digital filter to output value).
If CtL is far lesser than hysteresis time t (lesser than 1/5 - 1/10), there is no
difference if changing CtL. For example, when hysteresis time t is 100
seconds, then the control effect will be same no matter CtL=0.5 seconds
or CtL=10 seconds.
Principle for determining CtL:
a. When under time proportioning output, and using SSR or controlled silicon
as output actuator, the control period could be short (generally 4 seconds) to
improve control accuracy. When using relay open and close to control output,
short control period will be harm to the lifetime of mechanical switch, so the
control period is generally 20 seconds.
b. When the output is linear current, small CtL value can speed up the respond
against intelligent adjustment, and improve control accuracy. But the large
differential action may cause frequent change of output current. If the actuator
is regulating valve, and there are frequent valve actions, enlarge CtL properly
to slow down the valve action till it meet the requirement.
6.12 communication parameter "Addr, bAud"
6.12.1 Parameter Addr defines the communication address of the instrument,
its effective range is 0 - 63. Instruments in a same communication line should
be set with different Addr to distinguish from each other.
6.12.2 Parameter bAud defines the communication baud rate, its effective
range is 300 - 4800 bit/s
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