HF scientific MicroTOL Online Turbidimeter old series- 0-1000 NTU - Manual (Page 25)

MICRO TOL (12/04)
Rev. 2.7 19
Set the correct hour by pressing the
t or u button to change the displayed hour. When
you have selected the proper hour, press the
↵ button. After pressing the ↵ button, MIN
will be displayed and you will see the current minute of the hour.
Set the correct minute by pressing the
t or u button to change the displayed minutes.
When you have set the correct minute, press the
↵ button.
7.5 Programming the Alarms & 4-20 mA (if used)
If your instrument does not use the RS-485 option, the following menus will be displayed
after the date and time.
Two relays are provided that are designed to operate as two independent programmable
alarms. You must input three types of information to fully program each alarm:
1. The alarm function (HI, LO, or OFF)
2. The alarm set point (level at which the alarm activates)
3. The delay time for the alarm: the time that the set point must be exceeded prior to
alarm activation (prevents ringing in the relay)
These three items are described below:
Alarm Function: The alarms can either be turned OFF or programmed to operate in one
of two different manners:
1. HI alarm: the relay changes state when the measured turbidity level is higher than the
programmed alarm level for a prescribed amount of time.
2. LO alarm: the relay changes state when the measured turbidity level is lower than the
programmed alarm level for a prescribed amount of time.
Note: The relays automatically change state when an internal system failure is detected.
Alarm Set Point: The level at which an alarm activates is called the alarm set point. On
the instrument, the alarm set point is designated as “S/P”. The set point is adjustable to
any valid turbidity level over the range of the instrument in steps of 0.01 NTU.
Alarm Delay Time: The alarm delay times are used to prevent ringing of the alarm
when the measured turbidity level is close to the set point. The function of the delay
times is as follows:
Delay On: The turbidity level must exceed the alarm set point continuously for at
least this number of seconds before the alarm activates.
If the delay on time is set at 5 seconds and the process turbidity exceeds the
set point continuously for only 4 seconds, the alarm will not be activated.
However, process turbidity exceeds the set point continuously for 5 seconds or
more, the instrument will activate the alarm.