User Guide

current output). Output current are 0-10mA and 2-40mA.
stable stage is 700℃, while when the output is 0%, the temperature of
When oPI=2, output mode is time proportioning output, and AL1 act as
electric furnace is room temperature 25℃, then M50 (optimal value) is
output synchronizing with main output. Under this mode, the AL1 of the
700-25=675℃.
instrument can’t be used to output alarm signals as it’s used as output. M50 is mainly for adjusting the integral action of adjusting algorithm. The
Only AL2 is available for alarm signals (refer to 6.8).
smaller the M50, the strong the integral action. The larger the M50, the
oPL and oPH are the output low limit and high limit. Attentions: the setting weak the integral action (integral time will increase). But when M50=0,
of oPI should be in accordance with the module of main output. system will cancel integral action.
When oPI=1 (current output), oPL and oPH are as following:
0-10mA output: oPL=0, oPH=100
6.11.2 Rate parameter "P"
4-20mA output: oPL=40, oPH=200 P is inversely proportional to the measurement variation when the output is
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
P= 100÷increased measuring value per second, the unit is ℃ or 10
the ratio of open and close of relay (or ratio of high and low voltage defined units (when linear input). For example, when the output is 100%,
output of SSR) in a fixed period to realize output variation. Time no heat dissipation, and the temperature of the electric furnace increases
proportioning output could be regarded as a square wave, its period
1℃ per second, then:
is equal to control period Ctl. Output value is proportional to the duty
P=100÷1=100
ratio of square wave, varying from 0% to 100%. Users can use oPL P has influence to adjusting proportion and differential. When the P value
and oPH to limit the output range of time proportioning output. For increased, the adjusting proportion and differential action will increase
example, to limit the output within range 20%-60%, set oPL=20, proportionally; while when the P value decreased, the adjusting proportion
oPH=60. Generally, the default setting of time proportioning output is and differential action will decrease proportionally. P has no influence to
oPL=0, oPH=100, that is, no output limitation. integral action. Set P=0 is equal to set P=0.5.
(wave when output is 40% and 60%)
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.
6.10.2 Adjustment mode parameter "CtrL"
ITC-100 allows digital adjustment or professional PID adjustment.
6.11.4 Function parameter "CtL"
Select it by CtrL parameter. CtL value can be set between 0.5-120 seconds (CtL value 0 is equal to 0.5
When CtrL=0, adopt digital adjustment (ON-OFF). It’s only for
seconds). It reflects the operation speed of instrument control. For time
applications where the requirements are not strict. proportioning output (triggering by SSR voltage/relay/control silicon), it
When CtrL=1, adopt professional PID adjustment. It’s an improvement represents the control period of the instrument; for linear current output,
based on PID adjustment and fuzzy adjustment, suitable for various it controls the output fluctuation (time constant for digital filter to output value).
objects, and well control on fast changing objects and hysteresis. It’s If CtL is far lesser than hysteresis time t (lesser than 1/5 - 1/10), there is no
the default setting when product leaving factory. Under this setting, difference if changing CtL. For example, when hysteresis time t is 100
self-tuning could be launched by panel operation. seconds, then the control effect will be same no matter CtL=0.5 seconds
When CtrL=2, launch self-tuning. It’s same operation as launching or CtL=10 seconds.
self-tuning by panel operation. If another self-tuning is needed after
Principle for determining CtL:
self-tuning, set CtrL as 2 to re-launch self-tuning. a. When under time proportioning output, and using SSR or controlled silicon
When CtrL=3, adopt professional PID adjustment. After self-tuning, as output actuator, the control period could be short (generally 4 seconds) to
the instrument will apply such setting. Under this setting, no self-tuning improve control accuracy. When using relay open and close to control output,
is allowed from panel operation, thus to avoid maloperation to launch short control period will be harm to the lifetime of mechanical switch, so the
self-tuning. control period is generally 20 seconds.
b. When the output is linear current, small CtL value can speed up the respond
6.11 PID control parameters related to self-tuning “M50, P, t” and
against intelligent adjustment, and improve control accuracy. But the large
functional parameter “CtL”
differential action may cause frequent change of output current. If the actuator
PID control parameters M50, P and t are the control parameters for is regulating valve, and there are frequent valve actions, enlarge CtL properly
professional PID adjusting algorithm. M50, P, and t are determined by to slow down the valve action till it meet the requirement.
self-tuning. This instrument adopted the latest professional PID
adjustment which is a new algorithm enhanced with fuzzy logic. 6.12 communication parameter “Addr, bAud”
Following are the definition of each parameter.
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
6.11.1 Holding parameter "M50"
be set with different Addr to distinguish from each other.
M50 defines the deviation for measured value when the object is stable, 6.12.2 Parameter bAud defines the communication baud rate, its effective
and the output value is 50% (when oPI=1, the current is 5.0mA). For range is 300 - 4800 bit/s
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
Figure 7 diagram of time proportioning output
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