Pid/Pwm And Pid 4/20Ma Control Mode - YSI MultiDO 5400 User Manual

Low range control value must be < set point value. High range control value must
be > set point value. Low alarm value must be < low control value. High alarm
value must be > high control value.
Example - entering "63" for DO set point results in validation error because the
valid range for the DO sensor system is 0.00 to 60.0 mg/l. User must configure
value within valid range. In addition, the value cannot breach respective control
and alarm system values.
Example - configuring set point value of 8.00 mg/L with range low value of 8.00
mg/l results in validation error. Valid set point range is displayed at validation error
display. Press to return to numeric keypad to enter valid value.
Autofix occurs when a high or low control value is entered that breaches the set point
value. Autofix changes the high or low control value by one least significant digit
away from the set point value. The set point value is never adjusted.
Example - Entering 8.00 mg/L as the range low value when the set point value is
8.00 mg/L results in an auto fix of the control value. The invalid control value is
displayed at the sensor setup menu. Pressing
a value at numeric keypad. Press
with the autofix. A validation error window is displayed to show that the autofix has
occurred. Press to return to sensor setup menu. Verify that the autofixed
values are configured for user's specific application and reconfigure as needed. Press
to save configuration and return to Run Screen.
Configuring the 5X00
is not an option after saving
from the sensor setup menu to continue
YSI 5X00
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PID/PWM and PID 4/20mA Control mode

Configure PID/PDW and PID 4/20mA control mode at Sensor Setup menus. (PID
/PWM and PID 4/20mA control modes are also referred to as PID control modes).
PID stands for Proportional, Integral and Derivative. PWM stands for pulse-width
modulation. PID/PWM and PID 4/20mA control modes operate similarily but
use different output to control the control outcome. The difference is that a system
configured in PID/PWM control mode uses a relay as the output control device
and a PID 4/20mA control mode system, instead, drives a 4/20mA output device,
such a valve, to control the system. Both control modes use a complex algothrium
in determining the best way to sustain water system value(s) around a set point
using a relay PID/PWM (on/off) or a value PID 4/20mA. Both control modes can
be used to control an ouput device to maintain a certain water parameter at it's
set point. Both PID 4/20mA and PID/PWM control modes are feed back control
systems. Three factors determine how these control modes seek to maintain water
system value(s) around a set point. The three factors are:
-the error (distance) from present measurement of input to set point (present time);
-the duration of the error (accumulation of past errors);
-the speed at which the value is approaching the set point (predicts future errors);
PID/PWM and PID 4/20mA control systems are considered active whenever er-
ror exists away from the configured set point. PID/PWM and PI 4/20mA control
systems are flexible and can be tuned to keep water systems around their set points
even though the environment is exposed to disturbances that drive the input value
away from set point. An example of a PID control system that most readers will
be familiar with is a cruise control system in a car. Acceleration and deacceleration
adjustments are continually being made to maintain the car at a constant speed
or set point.
PID/PWM and PID 4/20mA control mode allows configuration of high and low
alarm systems which alarm systems activate peripheral devices and/or provide alarm
notification messages when alarm condition(s) exist.
Configuring the 5X00
YSI 5X00
159