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ENGLISH
Example PH: if the selected setpoint is 7.00 pH and hysteresis is set at 0.05, the two active points are 6.95 pH and 7.05 pH: within
this range, the setpoint is OFF and the outputs are blocked, outside this range the setpoint is ON (always in accordance with Acid or Alkaline
mode). The RX parameter (mV) works in the same way with mV values.
ADVANTAGES: assuring proper system control without straining the connected device.
DISADVANTAGES: the user must remember that the programmed hysteresis is slightly different from the required setpoint.
DELAY output response delay on setpoint
The Delay time blocks the output relays (max 999 sec. programmable) to ensure the outputs are active only when the sensor
measurements are stable, thus assuring the best results in terms of chemical balance.
PROPORTIONAL - PWM mode: Timed “Pulse Width Modulation”
PWM “pulse width modulation” supports a proportional mode on each setpoint activating at the pulse, with a change of the
Start/Stop cycle time according to the measured value with respect to the setpoint.
Pulse width: pulses are timed ON/OFF based on the distance from the selected setpoint (programmable), example: if the selected
setpoint is 7.00 pH and the measured value is 9.00 pH, and the selected value of the PWM mode is 1.50 pH, the proportional function starts
after reaching 8.50 pH with Time/Pause pulses and decreasing the active time while reaching the setpoint.
Cycle Time: selected value in the PWM mode 1.50 pH with a 60 second cycle (programmable), example: setpoint is 7.00 pH, at
measured value 8.50 pH = active time 60 sec - pause time = 0 sec; 7.75 pH active time = 30 sec - pause time = 30 sec… decreasing the
active time as a consequence while reaching the setpoint. The cycle time depends on many variables, such as: distance from the injection
point of the system to be treated, how fast or slowly the setpoint needs to react, chemical concentration, etc.
MIN Active Time: programmable. Defines the minimum time for which PWM is active; prevails over the selected settings. The pulse
modulation function is adjusted with 3 functions according to the following formula: Active Time in accordance with the selected formula =
(measured value - setpoint) / (period width * cycle time). If the result of the formula is < than that chosen with MIN Active Time, the latter
prevails on the former, example: measured value 8.50 pH; setpoint 7.00 pH / Period Width 1.50 * Cycle time 60 sec = active time 4 sec. If the
user has selected Active time min 5 sec, this will be the minimum PWM time and not 4 sec.
ADVANTAGES: the proportional function is more accurate than the ON-OFF mode.
DISADVANTAGES: to select the most accurate settings and assure the best results, the operator should be an expert.
ANALOGUE OUTPUTS IN CURRENT 4 -20 mA1 / 4-20 mA2
The instrument features 2 outputs with mA signal in current. The 4-20mA1 and 4-20mA2 signals follow the pH / RX settings
selected previously. The mA output provides two operating modes to be selected according to the system’s operational requirements:
mA DEVICE: this is a programmable function combined with the unit of measure of the pH or Redox in real time which makes it
therefore possible to remotely monitor devices such as data loggers, PLCs, recorders or other devices suited to processing remote signals
in mA. Value 4 mA corresponds to the minimum pH or RX value (mV), 20 mA corresponds to the maximum measurable pH or RX (mV)
value, the connected equipment will operate accordingly.
METERING ON SETPOINT: mA outputs control metering pumps suited to processing an mA signal on input. 4 mA corresponds to
the minimum pH or RX value (mV), hence the connected metering pumps will work at their minimum capacity. 20 mA corresponds to the
maximum measured pH or RX mV value hence the connected metering pump will work at its maximum programmed capacity (according to
the settings of the device).
ADVANTAGES: best possible results because the pulses are extremely accurate in relation to measured levels.
DISADVANTAGES: the user requires a specific metering pump or other device suited to processing an input signal in mA.
OVERDOSE TIME
With the overdose time alarm one can select a period during which the setpoint must be reached. If the setpoint is not reached
during this period of time, the instrument blocks output operations, including those in mA (metering pumps), the alarm is ON (displayed) and
triggers the relay 4 output (ALARM).
ADVANTAGES: preventing excessive doses of chemicals.
