Manual

YSI 5X00
145
YSI 5X00
144
PID/PDW Tuning
Each and every water system responds very dierently to peripheral control de-
vices due to many factors. Factors that can inuence the ability of a control device
to maintain a certain set point include size of system, peripheral equipment such
as pumps, lighting, system location and the like. While PID/PWM tuning is an
important and necessary requirement to properly congure the control system
it is outside the scope of this document to describe the tuning process. ere is a
wealth of information available on the www as well as in print. Please familiarize
yourself with additional information in order to further your understanding of the
PID/PWM control method.
Set Point
Congure the set point to be the value at which you’d like the system to ideally
operate at. DO set point can be congured in either mg/L or %Sat at the. Congure
at PID mode menu.
Control Up/Down
Congure the PID/PDW control system to either control up (Falling, to create a
control action to reduce down the system water parameter value) or control down
(Rising, to create a control action to increase up the system water parameter value).
A PID/PDW control can be used only to control the system by either driving the
system value up or down. A PID control cannot be used to drive the system value
both up and down.
PID/PWM Control Actions
Interval, Gain, Reset Interval
Conguration of three control actions allows for greater control and stablity of
a particular environment. e control actions are Gain (page 145), Reset/Inteval
(page 145) and Interval (page 145). ese three controls actions are closely inter-
related in terms of how the PID/PWM algothrium works. e objective is to tune
and congure these control actions in order that the corrective action (output con-
trol on time) performed by the 5X00 results in system stability. at is, the system
will hold the set point without oscillating wildly (overshooting or undershooting
by signicant amounts) over and under the set point. A large amount of ocillation
could cause irreparable damage to the system by dosing too large an amount, or too
small an amount, of a control dosing additive to the system stream.
AquaManager includes a PID Tuning tool which allows simulation of various control
action values and functions. e PID tuning tool should be helpful in mimicking
your system through simulation. e AquaManager PID Tuning tool is explained
in detail in the AquaManager Help System.
PID/PWM Interval control action
Range 1.00 to 999 (seconds)
Congure the interval control action to be the length of time a complete PID/PDW
control cycle takes. e control cycle includes both the control relay output on time
and the control relay output o time. Example: A 10 second control relay on time and
a 10 second control relay o time would represent a 20 second interval time. e 10
second control relay on time would be expected to decrease as the value reaches set
point. Interval, Reset interval and Gain control congurations are all interrelated in
the calculation of the control relay on time as the algothrium calculates the proper
corrective action.
PID/PWM Reset Interval control action
Range 0.00 to 100 (seconds)
Congure the Reset control action to be the rate at which the PID/PWM cycle re-
sets. In other words at what interval the past errors are erased and the PID/PWM
process begins a new cycle using new errors, and not past errors, in the PID/PWM
formula in calculating corrective action. Interval, Reset interval and Gain control
congurations are all interrelated in the calculation of the control relay on time as
the algothrium calculates the proper corrective action.
PID/PWM Gain control action
Range 0.01 to 10 %.
Gain is used to control the percentage of change in the output. Output increases with
greater gain. A high gain results in a large change in the output for a given change
in the error. A gain of “5” results in an additional 5% output relay on time for each
1% increase/decrease of the measurement. Tuning theory and industrial practice
indicate that gain should contribute the bulk of the output change. Interval, Reset
interval and Gain control congurations are all interrelated in the calculation of
the control relay on time as the algothrium calculates the proper corrective action.
Note:
- Once a PID/PDW control relay energizes the relay completes the interval cycle
based on the latest ratio error and does not automatically deenergize when
the set point is reached. e PID/PWM formula resets all values to 0 once
set point value is achieved and the formula is discontinued. is only occurs
aer the interval time expires.
Conguring the 5X00Conguring the 5X00